^L. planaxis.^ Somewhat larger than the last; wider; with a lower

spire; grayish in color, sometimes speckled with white; chest

nut-brown within. The columella is remarkably flattened, and a

portion of the whorl next bordering the columella is excavated as

though eaten away by the animal. These two species are often found

associated on the rocks. (Plate LXIX.)

GENUS ^Lacuna^

[Illustration: /Lacuna vincta./]

Closely allied to /Littorina/ is the genus /Lacuna/, one species of

which, ^L. vincta^, is very abundant on the New England coast. A

curious and distinguishing feature of this genus is the umbilicus,

which forms a lengthened groove along the columella. /L. vincta/

rarely exceeds one half of an inch in length, and is thin, with a

pointed spire of five whorls. It is either of a uniform horn-color,

or purplish, or banded with chestnut. It may best be found upon

marine plants in sheltered places, or may sometimes be gathered in

quantity from the roots of /Laminaria/ washed in by storms.

GENUS ^Tectarius^

The specific representatives of this genus are mostly tropical. ^T.

nodulosus^ is abundant in Florida. It is about one half of an inch

long, and has the flattened columella and round mouth characteristic

of /Littorina/. It is decorated somewhat elaborately by revolving

rows of nodules which cover the entire shell. Its station and habits

are the same as those of /Littorina/.

FAMILY ~CERITHIIDÆ~

In this family we meet with a somewhat new type of shell--the long,

turriculate shell, with many whorls and with a channeled [pg374]

aperture. The /Cerithiidæ/ include a large number of genera, mostly

tropical in distribution. Their shells are usually highly ornamented

in various schemes of sculpture, but they lack beauty in color. The

animal is provided with a siphon, as is indicated by the anterior

canal of the shell. The operculum is corneous, with a nearly central

nucleus.

GENUS ^Cerithium^

^C. floridanum.^ A very common species on the west coast of

Florida, also sparingly found at Hatteras. It has eight or ten

whorls, a gradually tapering spire, and a sharp apex; the aperture

is oblong, with a deeply cut anterior canal projected to the left

and backward (when the specimen is held apex up, with the aperture

toward the observer). The sculpture is elaborate, consisting of

many rows of revolving ribs, and close to the suture there are

circling rows of nodes. There is a curious hump just to the left

of the aperture, which is quite characteristic of the genus. The

color is whitish-gray; the length one and a quarter to one and a

half inches. Station, shallow water in lagoons and sheltered spots.

(Plate LXIX.)

^C. muscarum.^ Another Floridian species, somewhat smaller than the

last (one inch in length). It has heavy, prominent, transverse ribs

crossed by circling rows of chestnut spots, one heavy revolving

rib around the base; eight or nine whorls; a high-tapering spire;

and a sharp apex. The aperture is oblong, with the anterior canal

projecting to the left. The columella is arched; the color shining

gray to very light purplish. This very pretty little shell may be

gathered literally by the shovelful all along the west Florida

coast in sheltered spots, on sandy and shallow bottoms. (Plate

LXIX.)

^C. minimum.^ A still smaller Floridian shell, with jet-black

aperture and anterior canal projecting horizontally to the left.

The sculpture-plan is of revolving ribs and a series of white

granules just below the sutures. Its station is the same as that of

the last. Often the bottom of a lagoon will seem to be literally

paved with these somber-hued little shells. From Tampa Bay to

Charlotte Harbor they are very abundant.

GENERA ^Bittium^, ^Triforis^

These are allied genera, having numerous species upon our coasts, but

the shells are so small that the inexpert collector is not likely to

notice them. Hosts of these minute, turreted, decussated, blackish

shells are to be found on the wiry grasses of salt-marshes. They are

also found on algæ at low-water mark. In /Triforis/ the whorls turn

to the left. Range from Cape Cod to South Carolina. [pg375]

GENUS ^Cerithidea^

^C. scalariformis.^ This species has the suggestive outlines of the

family, but the aperture is simpler. The outer lip is considerably

thickened, sinuous, and yellow; there is a very slight notch at the

angle of the columella, and the lip serves for an anterior canal.

The apex is wanting by reason of the usual truncation of two or

three whorls of the spire. There are revolving ribs on the base;

longitudinal ribs elsewhere. The color is a dingy drab; within,

brownish-yellow. It is found in brackish water in Georgia and

Florida. This species is said to suspend itself from overhanging

vegetation by means of glutinous filaments. It may remain out of

water for an almost indefinite time. (Plate LXIX.)

^C. sacrata.^ A species very common on the mud-flats of San

Francisco Bay. It is a high-spired shell of ten heavily ribbed

whorls, with a series of revolving ribs on the body-whorl. The

outer lip is sinuous, and the columella is slightly twisted. It is

nacreous and brown within, dingy blue-black without. Length one

inch to an inch and a quarter. (Plate LXIX.)

FAMILY ~VERMETIDÆ~

GENUS ^Vermicularia^

[Illustration: /Vermicularia spirata./]

^V. spirata.^ This is a very curious creature when considered from

the point of view of the gasteropod mollusk. It seems at first as

though it would be better to regard it as a worm which had created

for itself a calcareous covering. But it is a true prosobranch

notwithstanding the fact that it has departed widely from the

conventional design in the fashioning of its shell. At first the

shell starts out in a regular form, and then the whorls become

separated, finally wandering about in a seemingly aimless manner.

The irregular prolongation sometimes measures ten inches in length.

The animal is in no way remarkable except in having the viscera

greatly elongated and the foot very short and broad. The color of

the animal is light brown with black spots; the shell-color is

rufous or ashy-white. Shells of this genus are often found grouped

together in an inextricable mass. It is found in shallow water from

New England to Florida.

FAMILY ~STROMBIDÆ~

This is a particularly interesting family, but it is tropical, and is

represented on the shores of the United States by only one [pg376]

genus, /Strombus/, of which we have but a few species. /Strombus/

is a scavenger,--a buzzard among mollusks,--and its sense of smell

is evidently very acute. Its eyes are much more highly developed

than the usual gasteropod visual organs, and they are placed at

the tip-ends of two very substantial eye-stalks or-pedicels. The

tentacles are slender and project from the eye-pedicels. The foot

is curiously developed; that portion of it which would naturally

constitute the creeping-disk is exceedingly small, but the metapodium

(the hinder part of the foot, upon which the operculum is situated)

is very large. The corneous operculum upon its end, which is far too

small to close the entrance of the shell when the creature retires

within it, looks like a claw. Instead of creeping along the sand,

/Strombus/ proceeds by jumps or awkward leaps, turning its heavy

shell first to one side, then to the other. The shell is usually

heavy, with the outer lip greatly thickened.

GENUS ^Strombus^

^S. pugilis.^ The very common Floridian species, often three to

four inches in height, with a short spire covered with nodes or

short, obtuse spines, which are also found upon the shoulder of the

body-whorl (sometimes smooth). The aperture is long, with a wide

notch in the outer lip and a posterior canal. Living specimens have

a tough, leathery epidermis covering at least the body-whorl. The

color is brownish. The columella is covered with a fairly thick

callous deposit, and, as within the aperture, is highly polished,

and deep purple, blackish-chestnut, or vivid carnation-red in

color. The smoother varieties have gone under the name of ^S.

alatus^, but the identity of the two species is assured. This

pugilistic /Strombus/ is a very active mollusk, and when placed in

a boat will sometimes effect its escape over the side in a most

surprising manner. The species is very abundant in all the shallow

waters of Florida. A piece of meat on a string, left overnight in

some sheltered sandy spot where there are from six to eight feet of

water, will surely attract them. In Florida, where the waters teem

with life, unless the bait is protected in a wire cage, the chances

are that the hosts of crustaceans and fish will make away with it

long before the strombs can arrive on the scene. (Plate LXX.)

^S. gigas.^ One of the largest of gasteropods, very common on the

Florida Keys and also occurring in southern Florida. Hundreds of

thousands of these shells have been sent to Europe from the Bahamas

to be cut into cameos. This familiar shell is to be seen everywhere

in the South, placed about flower-gardens and lining the paths

and walks in yards. It is generally known in Florida and the West

Indies as the "conch-shell." The animal is used as food in Key

West, and is very generally eaten throughout the Bahamas. From

their habit of eating [pg377] these animals the natives of some

of the Bahama Islands are themselves called "Conchs." The rich pink

color of the shell is very striking.

There are perhaps seventy-five or eighty species of /Strombus/

inhabiting the tropical seas, and many of them are highly prized by

collectors on account of their great beauty.

[Illustration: PLATE LXIX. 1, Littorina angulifera, twice natural

size. 2, Littorina scutulata, much enlarged. 3, Littorina planaxis,

enlarged. 4, Cerithium floridanum. 5, Cerithium muscarum. 6,

Cerithidea scalariformis, enlarged. 7, Cerithidea sacrata.]

[Illustration: PLATE LXX. 1, Strombus pugilis. 2, Cypræa exanthema.

3, Trivia pediculus. 4, Trivia californica. 5, Trivia quadripunctata.]

FAMILY ~CYPRÆIDÆ~

GENUS ^Cypræa^

/Cypræa/ is one of the "aristocratic" genera. Whether the shell

or the animal itself is considered, there is probably no genus of

mollusks which offers so much of beauty and interest to the collector

and student. The genus is a tropical one, and finds its metropolis

among the coral-fringed islands of the equatorial Pacific. Despite

their brilliant colors and general attractiveness, the cowries--for

such is their popular name--are very modest and shy; they prefer to

hide among rocks, where they may be secure from molestation, for

probably their conspicuous appearance is a real source of danger

to them. In the animal of /Cypræa/ the mantle is provided with two

large lateral lobes, which are reflexed and meet over the top of the

shell; thus, when the mantle is fully extended, the shell is entirely

concealed. These mantle lobes are often furnished with numerous

forked, tufted, or ramified filaments. The foot is long; there is

no operculum. The color of the animal is often very striking in its

intensity. A description of the cowry-shell is hardly necessary, so

familiar is every one with it. A deposit of enamel is made all over

the shell, and its painting and decoration, usually very elaborate,

is reserved for the adult as a final process in the artistic

completion of its home. The aperture is as long as the shell, is

channeled at both ends, and is toothed along both margins. The spire

is insignificant and is concealed by layers of enamel. In the young

the shell has a very different appearance, resembling a sharp-lipped

/Oliva/, and its scheme of coloration may be entirely different from

that employed by the adult.

Among the /Cypræidæ/ are many remarkable species. The splendid

^Cypræa aurantia^, a native of the Fiji Islands, is one of the

shells most sought after by enthusiastic collectors. The natives

[pg378] learned its value long ago, and hold specimens of it at very

substantial prices. It is worn as an ornament by chiefs and as a mark

of distinction. The well-known ^C. moneta^, also a native of the

Pacific Islands, has been very extensively used as money throughout

the South Seas and in Africa. There are many collectors of shells who

confine their efforts almost exclusively to this and to one or two of

the other "aristocratic" genera. From an esthetic point of view this

is very natural, but biologically the less pretentious mollusks are

quite as interesting.

Of the one hundred and fifty or more species in existence only three

are to be found upon the Atlantic coast of the United States, and the

chances are decidedly against the finding of any of them north of

extreme southern Florida.

^C. exanthema.^ A species not uncommon at Key West, where it may

be seen slowly crawling about the mangrove roots near the water's

edge. It attains a length of from four to six inches, and is so

highly polished that a good specimen could be used as a mirror. In

color it is shining, light chestnut, clouded with purple; the lips

are a dark, very rich chestnut; over all are whitish spots which

appear to shine forth from beneath the enamel. Lengthwise along

the middle of the back is a zone of lighter color which reflects a

purplish sheen. (Plate LXX.)

^C. spurca.^ Another Floridian species, properly belonging to the

West Indian fauna. It is not more than one half an inch long, and

is white in color, but it is so thickly dotted with yellow spots

upon the back that it would pass for a yellow shell. The base is

pure white. The surface of the shell glistens in the light.

GENUS ^Trivia^

In the genus /Trivia/ the shell is shaped in every way like that

of /Cypræa/, but its surface is never smooth. In the middle of the

back is a longitudinal groove, from which run transverse ribs, which

continue around to and enter into the aperture. The shells are always

small, never exceeding one half of an inch in length, and their color

is generally reddish or brownish, passing to pink.

^T. pediculus.^ A Floridian species, first described by the great

naturalist Linnæus. Like most of the descriptions of the earlier

naturalists, this is very short and inadequate, and would apply

equally well to almost any /Trivia/. The color is rose-pink, with

several large brownish splashes on the back. The spire is entirely

hidden. It is found in shallow water in pools, and on the beach

after storms. (Plate LXX.) [pg379]

^T. quadripunctata.^ Much smaller than the preceding; rose-red,

with four conspicuous reddish-brown dots on the back, two on each

side of the median dorsal groove. Found in Florida. (Plate LXX.)

On the California coast are also several species of /Trivia/ and

one /Cypræa/, but they belong to the Southern California peninsula,

and are not commonly found farther north than Santa Barbara. The

cowry is called ^C. spadacea^; it grows to a length of about two

inches, is highly polished, with white base and sides, and is

bright chestnut above. As is usual in the cypræas, the spire is

covered with enamel.

^T. californica.^ A species found at Monterey and thence south.

It lacks the median dorsal groove, and has a whitish color-streak

instead. The ribs are white, and the ground-color of the shell

is dark brownish-red. These little shells, when found upon the

beach, are called "coffee-shells," from their somewhat striking

resemblance to the coffee-bean, being flat on one side and rounded

upon the other, and otherwise resembling it in size and color.

(Plate LXX.)

^T. solandri.^ This species may be found at Santa Barbara and San

Diego. It is twice as large as the last species, and has a very

deep groove in the back and widely separated ribs. Color rose to

brown. The groove on the back penetrates into the white portion of

the shell.

FAMILY ~DOLIIDÆ~

This small family furnishes two conspicuously handsome species

belonging to the genus /Dolium/, which range from Hatteras southward

into the West Indies.

GENUS ^Dolium^

^D. galea^ and ^D. perdix^. The animal in both of these species

has a relatively large foot, which spreads out while in the act

of creeping and seems far too bulky ever to be withdrawn into the

shell. It is square in front, and, bulging out far to each side,

tapers to a blunt point behind. The most noticeable feature of the

animal, however, is the great development of its proboscis, which

is quite as long as the shell itself. The siphon is also long and

is curved over the back of the shell. The operculum is wanting in

adult specimens. The shell of /D. galea/ sometimes attains a length

of eight inches, with a diameter of about six inches; the other

species is not quite so large. They are both ventricose, thin,

inflated shells, with large body-whorls and crenulated lips. Both

are slightly umbilicated and ornamented with revolving, regularly

spaced ribs. The ribs of /D. perdix/ are not so highly raised,

but they are painted with light reddish-brown spots. /D. galea/

is white, with a lower spire and deeply channeled sutures. (Plate

LXXI.)

GENUS ^Pyrula^

^P. papyratia.^ One of the commonest as well as one of the

handsomest of American shells. It is a Floridian species, found in

shallow water and on sandy bottoms. The animal greatly resembles

that [pg380] of /Dolium/, except that it has two side-flaps,

which, when extended, partially inclose the shell. The shell is

thin, with an almost flat spire and a greatly enlarged body-whorl.

The aperture is flaring, and is drawn out anteriorly into a

tapering canal, which gives to the shell the outlines of a pear.

The ornamentation is revolving, but not highly raised, and there

are ribs with very distinct longitudinal lines of growth between.

The color is pure white, or sometimes yellowish, with rufous spots;

within it is golden. This attractive shell is usually from three to

four inches in length, but is sometimes found considerably larger.

(Plate LXXI.)

FAMILY ~CASSIDIDÆ~

GENUS ^Cassis^

The cassides, commonly known as the "helmet-shells," are carnivorous

mollusks, which lead an active life in sandy stations, prowling

about in search of bivalves, upon which they prey. They have a large

siphon and a fairly large and extensible proboscis. The foot is

broad and strong, being well adapted for plowing through the sand.

The shell of /Cassis/ is large, generally heavy and inflated, with

a short spire and a short, recurved anterior canal. The lip is much

thickened. Upon the Atlantic coast of North America there are four

species of /Cassis/. They are all properly West Indian in their

faunal relations, but have found lodgment on the American shore at

various points. All of them have been taken in the neighborhood of

Cape Hatteras, two of them in West Florida, and two in Texas.

^C. tuberosa.^ A large, heavy shell, often from six to eight inches

in length, with a flattened spire. The aperture is long and narrow,

with large white teeth upon the outer lip, which is also greatly

thickened. The columellar lip is ribbed. A heavy deposit of enamel

to the left of the columellar lip gives the shell a triangular

outline. A row of very large nodes upon the shoulder of the

body-whorl and two rows of obsolete nodes below are characteristic

features of this species. The color is light yellowish-brown

suffused with pink. The aperture and the columellar callosity are

flesh-tinted, with chestnut trimmings. The anterior canal is deep

and recurved.

^C. cameo.^ A species of about the same size as the last, but

more ovate or ventricose in form. It is coarsely striated, with

elevated growth-lines, and has circling rows of large, rib-like

elevations, having sometimes nodes upon the body-whorl. The

columella is conspicuously ribbed and greatly expanded. The outer

lip is thickened, and has lamelliform teeth within. Flesh-colored;

teeth white; purple-brown trimmings. A great many of these shells

are sent yearly from Nassau [pg381] to Italy, where they are used

in cameo-cutting. It is owing to the fact that the substance of

these shells is deposited in layers of different colors that they

are available for this purpose. There are about fifty species of

helmet-shells, the one most valued for cameo-cutting being known as

the black helmet, /C. Madagascarensis/.

^C. testiculus.^ A species found outside of the West Indies only

at Key West and at Hatteras, where the Gulf Stream has brought so

many West Indian forms, and left them at the point where it takes

its oblique course away from the shore. This pretty species is

smaller than the others just described. It has a low, depressed

spire; longitudinal ribs crossing wide, flat revolving ribs; a

long, narrow aperture; and a reflexed and thickened outer lip,

also toothed. The columella is thickened and ribbed. The anterior

canal is recurved over the back of the shell, as is usual in the

genus. The color is bluish, with dark spots. There are square black

spots on the reflexed lip; the aperture is pink, and the teeth

and columellar ribs white. This species is exceedingly common at

Nassau, and plays havoc with the more slowly moving bivalves, which

it devours. (Plate LXXI.)

^C. inflata.^ Perhaps the commonest species of /Cassis/ on our

coast. It is reported to be common at Beaufort, South Carolina, yet

it is not so frequently met with out of the West Indies as some

earlier collectors would have us believe. Beach-worn specimens,

however, are not unusual all along the Florida coast. It attains

a size of from three to four inches, and is a rounded, globose,

ventricose shell, with a higher spire than is usual in this

genus. The surface is almost smooth, the series of revolving ribs

being scarcely raised on the body-whorl. The lip is thickened

and reflexed, with prominent lamelliform teeth which continue as

internal ribs. The lower portion of the columella is calloused and

roughly granulated. The color is bluish-white, glazed, with large

square brown spots. The region of the aperture is pure white.

The collector should not remain content with a specimen or two

of the poor beach-worn shells of this species. In general, this

advice applies to the collection of all specimens. One can get

no idea of the sculpturing and painting of shells from dead and

worn specimens. It is quality rather than quantity that makes an

interesting cabinet. (Plate LXXI.)

FAMILY ~MURICIDÆ~

SUBFAMILY ~MURICINÆ~

It seems like making a long leap to pass suddenly from the

/Cassididæ/ to the /Muricidæ/. In the natural biological order, as

it appears in our present state of knowledge, a host of families and

genera intervene between these two. But they are omitted here, either

because they do not conspicuously occur upon our own shores, or

because they are free-swimming pelagic mollusks, which live only far

out at sea and rarely are found on the beaches. The family /Muricidæ/

is an exceedingly large one, including a [pg382] bewildering number

of well-characterized genera. It has many representatives in every

sea, but, as is apt to be the case, the finest and most striking

species are tropical. The animal is not peculiar in any way, being

altogether a conventional prosobranch gasteropod, with moderately

long foot, and the usual tentacles placed upon a small head. There is

a retractile proboscis, which suggests carnivorous habits. In reality

the /Muricidæ/ are perfect pirates among the /Mollusca/, attacking

nearly every species they encounter, piercing its shell and devouring

the unfortunate inhabitant. They live in rocky and gravelly places or

about coral reefs. Their shells are seldom colored, except about the

aperture. What the shells lack in color, however, they fully gain in

oddness of form and in sculpturing. The anterior canal varies from a

mere notch to an astonishingly long channel. The tendency to nodes,

varices, spires, and varicose processes in general is a prominent

feature of the family.

There are several genera, with numerous species, upon the east and

west coasts of the United States, but we can do no more here than

mention those which are very common.

GENUS ^Murex^

Of this tropical genus there are two Floridian species--/M. rufus/

and /M. pomum/. The genus has been very extensively divided into

subgenera, based upon shell-characters alone. Some of these subgenera

are usually accepted at full generic value, and their substitution

for the old, well-established name /Murex/ is to be expected. These

two Floridian species fall within different subgeneric lines, and the

student who goes to a museum to compare his catch with the labeled

specimens on exhibition will probably be puzzled to find his two

murices named /Chicoreus rufus/ and /Phyllonotus pomum/ respectively.

But for our purposes the name /Murex/ will do well enough.

^M. rufus.^ This species scarcely ever exceeds three inches

in length. Its spire is moderately high, and the aperture is

oblong-ovate, with a long, slightly curved, and almost completely

inclosed anterior canal. Through the end of this the fleshy siphon

projects in life. The shell is most extravagantly sculptured--so

intricately that it is difficult to [pg383] describe it. Its

most conspicuous feature is the large foliaceous varices which

cross the whorls, projecting almost one fourth of an inch from the

body of the shell. Between each of these varices is a large node.

There is, besides all this, a system of pronounced revolving ribs

which cross the varices and nodes, giving to the shell a greatly

roughened appearance. The interior is bluish-white. The operculum

is corneous, with a subterminal nucleus. Unfortunately, this really

handsome shell is usually incrusted with coralline or calcareous

matter, which must be removed with acid before a good idea of

its appearance can be had. In color it is reddish-brown to dark

chestnut on the varices. It is very common on the west coast of

Florida, but rarer elsewhere. (Plate LXXII.)

[Illustration: PLATE LXXI. Dolium galea. Dolium perdix.

Pyrula papyratia.

Cassis testiculus. Cassis inflata.]

[Illustration: PLATE LXXII. Murex rufus. Murex pomum. Ocinebra

poulsoni, enlarged. Pteronotus festivus. Cerostoma foliatum.

Cerostoma nuttallii.]

^M. pomum.^ A more abundant species, found all along the coast

from Hatteras to Texas. It is not so elongated as the last, and

its sculptural design is much less exaggerated. Between each of

the varices are two nodules. The aperture is oblong-ovate, and

the anterior canal is nearly closed and recurved toward the back.

Revolving ribs cross the varices and nodules. The color is ashen,

with chestnut tips upon the nodes and varices, and chestnut-colored

patches about the aperture. The varices are simple and not

foliaceous as in /M. rufus/; the shell is more globose. Length two

to three inches. (Plate LXXII.)

^M. (Phyllonotus) fulvescens.^ The largest of the American murices.

It is not commonly found except in Texas.

GENUS ^Trophon^

[Illustration: /Trophon clathratus./]

^T. clathratus.^ A fairly common shell of the Maine coast;

although it belongs to a deeper zone than that of the tides, it

is occasionally found after storms upon the shore. It is a small

fusiform shell, with many prominent longitudinal ribs and a

produced anterior canal. /Trophon/ is a boreal genus, which finds

the best conditions for life in the icy waters of Labrador and

Greenland.

GENUS ^Urosalpinx^

The genus /Urosalpinx/ is closely allied to /Murex/ and /Trophon/.

Several of its species are found on the east coast of the United

States.

[Illustration: /Urosalpinx cinerea./]

^U. cinerea.^ This well-known species is regarded by Chesapeake and

Long Island Sound oystermen much in the light of a plague. These

active predaceous mollusks live upon bivalves, and preferably upon

oysters. They bore a small round hole through the shell of their

helpless victims, and then proceed to extract the succulent, fleshy

animal from within. The oystermen call them by the suggestive

name of "drill," and wage incessant warfare upon them. In some

years these mollusks appear to go into partnership with the large

starfish, /Asterias/, and the combination of the two can soon

destroy any oyster-bed. The original home of this destructive

little creature is presumed to be in Chesapeake [pg384] Bay, but

the transplanting of oyster-spat thence to Long Island Sound has

introduced the enemy at the same time. The species has a wide range

from Florida to Cape Cod, and locally north of that point; in fact,

it may be counted upon to appear wherever there are oyster-beds.

The shell is dingy gray in color, and its whorls are crossed by a

dozen or more rib-like undulations, and numerous revolving striæ.

The anterior canal is produced, and is yellowish-brown within.

Length under an inch.

GENUS ^Eupleura^

^E. caudata.^ A curiously flattened shell which has close family

connections with that last described. The peculiarly flat

appearance is due to the fact that there is a rather wide varix

upon each side of the shell. It is a small species, never more than

an inch in length, dingy gray, with longitudinal undulations upon

the whorls, and a long, narrow anterior canal and crenulated lip.

The animal is white and yellow, and is notable for its activity.

Found from Maine to Florida, about low-tide mark.

[Illustration: /Eupleura caudata./]

On the west coast of the United States occurs a striking development

of a group of the /Muricidæ/ of a curious foliaceous appearance,

belonging to the genera /Pteronotus/, /Ocinebra/, and /Cerostoma/.

GENUS ^Pteronotus^

^P. festivus.^ The shell is marked by three well-raised varices

upon each whorl, which are reflexed backward; between each varix

is a rounded knob. All is covered with numerous spiral lines

of sculpture, which upon crossing the varices are frilled. The

aperture is oval and white within; the anterior canal is entirely

closed and is reflexed slightly over the back. Length two inches;

color dingy white. Found on the southern coast of California.

(Plate LXXII.)

GENUS ^Ocinebra^

^O. poulsoni.^ This has the same dingy white color as the species

last described. Its plan of sculpturing is somewhat different and

consists of a series of rounded varices, about nine to a whorl,

crossed by spiral lines. The anterior canal is open, and just

within the white aperture, upon the inner side of the lip, is a

series of five or six little round teeth. This species frequents

the waters near San Diego, and sometimes grows to be two inches in

length. (Plate LXXII.)

^O. lurida.^ A much smaller species than the last, being not more

than one half to three fourths of an inch in length. Very common

at Monterey and in San Francisco Bay. It is strongly marked with

spiral lines covering the longitudinal undulations usually found in

this genus, but which are less prominently developed in this case.

There are several species of small ocinebras upon the California

coast, but they are not easily determined without a more critical

examination [pg385] than we are giving our specimens. They are

^O. interfossa^, a small shell with deep spiral grooves, sharp

varices, and deep sutures; and ^O. circumtexta^, also small, but

heavy, short-spired, with scalloped or crenulated outer lip.

GENUS ^Cerostoma^

^C. nuttallii.^ A species belonging to the southern coast of

California. It may be recognized at once by two prominent

characters: first, a horn-like projection from near the base of the

outer lip, and, second, the tumid varices alternating with rounded

knobs. It has no spiral series of lines like those in /Pteronotus

festivus/; and it has a row of five or six little teeth upon the

inner side of the aperture, like those in /Ocinebra poulsoni/.

The anterior canal is closed. It is about two inches long. (Plate

LXXII.)

^C. foliatum.^ A shell somewhat like the last, but almost twice as

large, with heavy wing-like varices (three upon each whorl), made

up of overlapping plaits. The knobs between the varices are much

smaller, while the revolving ribs, though fewer in number than in

most of these west-coast murices, are heavy and large. The aperture

is oblong, the anterior canal closed. There is a "horn" near the

base of the aperture, as in /C. nuttallii/, but no row of teeth

upon the under side of the lip. The color is dingy white. (Plate

LXXII.)

In the waters of Oregon and Washington there are a few trophons and

other forms similar to the east-coast genera. These no doubt belong

to the boreal and arctic faunal provinces, and have spread over

both the Atlantic and Pacific northern regions.

SUBFAMILY ~PURPURINÆ~

This is considered a subfamily of the /Muricidæ/, and the group

therefore bears the subfamily termination /-inæ/. There is no vital

difference between it and the subfamily /Muricinæ/. The operculum in

the /Purpurinæ/ has a lateral nucleus instead of a subterminal one,

but beyond this there are no essential differences. The shell of the

purpuras is generally heavy and solid, being adapted to a life among

rocks which are exposed to the beating of the surf. There is a lack

of that extravagant sculptural design so characteristic of the true

murices, most of the purpuras being comparatively smooth, in order,

no doubt, that they may offer as little resistance as possible to the

rushing, seething waters of exposed rocky shores.

The /Purpurinæ/, like some of the murices, when mutilated, exude a

reddish-purple fluid. On account of this, the ancient Romans used to

gather great quantities of certain Mediterranean forms belonging to

these families, place them in large mortars, [pg386] and grind them

up, shell and all. A garment dipped in the mixture and then exposed

to the sun would receive a rich purple dye. This was the basis of the

famous "Tyrian purple." The process was lost, and was rediscovered

many centuries later, but it was long ago abandoned in favor of the

far superior modern chemical dyes.

GENUS ^Purpura^

[Illustration: /Purpura lapillus./]

[Illustration: The same; a younger specimen.]

^P. lapillus.^ No one who has ever spent an observant hour among

the rocks at low tide, on the shores of Massachusetts or Maine,

has failed to notice the myriads of /P. lapillus/ clinging to

the barnacle-covered boulders, or slowly creeping about in the

tide-pools. This rather pretty little mollusk is a native of Great

Britain, and there attains its greatest development and exhibits

best its marvelous range of variation. It is presumed to be an

immigrant in American waters, having found its way across the sea

by Iceland and Greenland, and thence down the coast. As it is a

cold-water animal, and can only survive in open, rocky stations,

it will probably never pass south of New York. It is difficult

to describe this well-known species because it is so extremely

variable. There is an individuality about the species which causes

it to be recognized at once, yet its details are elusive. It is

never more than one and a half inches long (in the United States),

and varies in color from white through yellow to chocolate. Often

it is banded in yellow or brown. Near the only sand-beach of Bar

Harbor is a colony with vermilion bands. The shell varies from a

smooth to an exceedingly rough exterior, the latter being caused by

raised scales along the lines of growth, which make the shell even

prickly to the touch. Of this latter form there is a large colony

on Campobello Island. Numerous coarse revolving ridges are common.

The columella is flattened and smooth, and its lower portion is

a little twisted. The anterior canal is short. /P. lapillus/ has

been accused of attacking clams and boring their shells, as does

the predaceous /Urosalpinx cinerea/, but the accusation is not well

founded. /Purpura/ is carnivorous, and no doubt destroys many young

barnacles; but with its short and small foot it would find great

difficulty in digging in the sand for clams.

In Florida waters there are several purpuras, which properly belong

to the West Indian fauna, but enjoy an extensive range.

^P. patula.^ This species has a rounded body-whorl, and sometimes a

low spire, which give it much the appearance of a large limpet. Its

back is decorated with rows of nodules in regular order, forming

a spiral series. The chief point of distinction is the deeply

excavated, broadened, and flattened columella-lip of salmon-color.

A portion of the whorl itself is worn down and made smooth by being

dragged over sharp coral rocks, revealing underneath the rough,

incrusted exterior, a transparent colorless shelly substance. Dark

and chestnut-colored [pg387] patches and spots adorn the outer

lip. The shell is from two to two and a half inches long. (Plate

LXXIII.)

^P. hæmastoma.^ Like its relative, /P. lapillus/ of Northern

waters, this species is so variable as almost to defy description.

The form that usually occurs from Hatteras to Florida is of a

bluish-gray color, and is indistinctly encircled with narrow yellow

zones, which are crossed by somewhat vague longitudinal waves of

black. The columella and outer lip and interior are orange-yellow.

The spire is moderately high, with a sharp apex. The whorls are

noduled upon the shoulder. There are revolving grooves throughout,

even within the aperture. A Texan variety of this species has

a much more elevated spire, with channeled sutures, and small

aperture of bright salmon-color.

Upon the Californian coast there are three species of /Purpura/,

which markedly resemble the /P. lapillus/ of the Maine shores.

Their extreme variability has given rise to much confusion in their

nomenclature; the multitude of names given by numerous authors to

the varietal forms of these three species constitute a list of

synonyms which is appalling to the systematic student.

^P. crispata.^ With very few modifications, a description of /P.

lapillus/ would apply to this species, which occurs commonly at San

Francisco and ranges north. /Crispata/ is possibly heavier, with a

smaller aperture, and with four or five round teeth upon the inner

white surface of the thickened outer lip. It ranges in color from

pure white to dark brown and is sometimes banded. The surface may

be smooth or rough, and is sometimes ruffled all over with wrinkled

frills. Length one and a half inches. Its habits and station are

much the same as those of /P. lapillus/, of which it is possibly

a descendant, somewhat modified by changed environment. (Plate

LXXIII.)

^P. lima.^ A less common species, with rounded whorls and channeled

suture, and about fifteen spiral grooves upon the whorls. The color

is light brown; the length from one quarter of an inch to one inch.

^P. saxicola.^ A shell exceedingly abundant along the whole

Californian coast, living under quite the same conditions as the

purpuras already described. It is smaller than the last two, being

always less than an inch in length. It also runs through the gamut

of variations as to color-scheme and sculpturing, but always

preserves a certain individuality. There is a tendency to a small

umbilicus; the outer lip is sharp; the columella is flattened and

slightly twisted; and anterior canal is short, and bears to the

left. A smaller aperture, with relatively thicker shell, seems to

be all that distinguishes it from the smaller varieties of the

east-coast species. (Plate LXXIII.)

GENUS ^Monoceras^

This genus, which is very closely allied to /Purpura/, is almost

wholly confined to the west coast of the United States. The name is

given on account of a peculiarity, which has, however, already been

noticed in /Cerostoma/, namely, a horn-like projection from the basal

portion of the outer lip. In all other respects this genus is nothing

but a true /Purpura/. [pg388]

^M. lapilloides.^ The shell in this species is about an inch in

length, and has markings which give it a striking resemblance to

granite. A row of small round denticles upon the inner surface

of the lip is a characteristic already noticed in some of the

west-coast murices. Their station is the same as that of the

purpuras--between the tides on rocky, exposed shores. (Plate

LXXIII.)

^M. engonatum.^ This species has sharply ridged whorls, and

revolving ribs with wavy growth-lines between them. In other

respects it is almost identical with the last described. It is

often found mingled with the seaweed which covers rocks between

tides, and, when moist, simulates the color of its surroundings.

(Plate LXXIII.)

GENUS ^Chorus^

^C. belcheri.^ This family cannot well be left without at least

a mention of this large and rather handsome species. /Chorus/ is

a genus of but few species, confined to the Pacific shores of

North and South America. This particular species does not reach as

far north as San Francisco, but may be taken at low tide in the

vicinity of San Diego. The prominent feature of the shell is the

posterior canal, which, being abandoned as the growth of the shell

continues, leaves a series of hollow, folded spiny processes upon

the shoulder of the body-whorl, which appear like jagged points

upon the spire. (Plate LXXIII.)

FAMILY ~COLUMBELLIDÆ~

This is a large family of small but often exceedingly beautiful

shells. Their distribution is mostly tropical, but the list of

North American species is a very generous one indeed if the

deeper-water forms are included. The animal is quite the same as in

the /Buccinidæ/, to be described later. (See also description of

/Buccinum undatum/ on page 330.) The shells are usually quite solid,

with a long, narrow slit for an aperture; the outer lip is thickened

on the inside, especially about the middle portion, and is deeply

toothed; and the lower portion of the columellar lip is also ribbed

or toothed.

GENUS ^Columbella^

^C. mercatoria.^ This Antillean species is found in Florida, and

is one of the gems among the American shallow-water shells. Its

height is about one half of an inch. It is decorated with revolving

grooves and with a variously patterned color-scheme of broken

yellow or reddish [pg389] lines on a white background, or of

white splotches on a brownish background. (Plate LXXIV.)

[Illustration: PLATE LXXIII. 1, Purpura patula. 4, Monoceras

lapilloides. 2, Purpura crispata. 5, Monoceras engonatum. 3,

Purpura saxicola, enlarged. 6, Chorus belcheri.]

[Illustration: PLATE LXXIV. 1, Columbella mercatoria, enlarged.

4, Nassa fossata, about natural size. 2, Columbella (Amphissa)

corrugata, enlarged. 5, Nassa mendica, enlarged. 3, Columbella

(Astyris) gausapata, much enlarged. 6, Nassa perpinguis, enlarged.

7, Nassa tegula, enlarged. 8, Siphonalia kellettii, reduced. 9,

Tritonidea tincta.]

^C. (Anachis) avara^, and the variety ^C. similis^. These rather

slender shells, about one half to three fifths of an inch long,

occur from Florida northward to Cape Cod. The upper whorls are

smooth, the lower ones are undulated with vertical costæ (ten

to thirteen), and the body-whorl is encircled below the middle

by a series of revolving, closely set grooves. The aperture is

typical of the genus, though less strongly marked by internal

callosity on the outer lip and with less prominent teeth than in

/C. mercatoria/. The greater development of the revolving grooves,

which spread over the entire surface of the body-whorl and cross

the costæ, producing a granulated surface, constitutes the variety

/C. similis/. The color is brownish, with white reticulations.

This species is to be found in considerable abundance in sandy mud

and among stones and algæ about low-water mark. At New Bedford and

Martha's Vineyard, and on Cape Cod, it may always be taken. It is

also common at Norfolk and along the Virginia and Georgia coasts.

^C. (Astyris) lunata.^ One of the characteristic eastern-coast

shells, which, like the last species, ranges from Cape Ann in

Massachusetts to the West Indies. It occurs about low-tide mark

and just below, upon stones and algæ, or crawling about on a soft

bottom. On account of its generic features, combined with the

peculiar coloration, the species cannot be mistaken. The latter is

a ground of reddish-brown or fawn, with encircling rows of large

white or yellowish spots. The whorls are quite smooth. Length not

over one fifth of an inch.

The collector soon learns to recognize the variable forms of

these northern-range columbellas. They are not a difficult group,

for once their generic position is established by the characters

of the aperture (which are constant) the species can readily be

determined, notwithstanding their tendencies to vary from the type.

Californian waters also have several columbellas. The conchologists

of the west coast have preferred to apply to their shells, and

indeed to employ in general use, a large number of subgeneric names

in place of the ordinarily accepted generic ones. The result of

this is to confuse at first the student of conchology, who, though

fairly familiar with the molluscan genera, finds himself perplexed

when he confronts a list of west-coast shells. Thus the two common

Californian columbellas are /"Amphissa" corrugata/ and /"Astyris"

gausapata/, these two species belonging to different subgenera of

the genus /Columbella/.

^C. corrugata.^ This shell finds its metropolis in Puget Sound,

but occurs also along the Californian shore. The aperture is wider

than is usual in this genus. The surface is deeply wrinkled by

longitudinal costæ and is encircled by revolving grooves. Length

one half of an inch; color red, or orange to light brown. It is

found in shallow protected waters. (Plate LXXIV.)

^C. gausapata.^ This species lives in great numbers about the roots

of eel-grass. It is very small and smooth, with a rather high

spire. The color of the spire is deep brown; the body-whorl is

lighter in color. Occasionally the body-whorl is obtusely carinated

just below the suture. This little shell is very common upon many

beaches after heavy winds, but it should be sought for at very low

tides and gathered alive. (Plate LXXIV.) [pg390]

FAMILY ~NASSIDÆ~

These are familiar, and often very characteristic, littoral shells in

all parts of the world. Where they exist at all they are generally

to be found in astonishingly large numbers, sometimes even crowding

out all other mollusks. They are exceedingly active and predaceous,

feeding upon other mollusks, whose shells they bore through by means

of the sharp teeth upon their lingual ribbon. The /Nassidæ/ of the

east coast find a relentless enemy in the small hermit-crabs, which

attack them, drag them from their coverings, and then proceed to

occupy the empty shells themselves; the torn and lacerated /Nassa/

animal is thereupon leisurely eaten, a retribution probably well

deserved. The animal of /Nassa/ (the principal genus of /Nassidæ/)

is peculiar in having frequently a bifurcated tail; or, to speak

more correctly, the posterior end of the foot is terminated by two

appendices. It has a long siphon, and eyes placed upon the outer

sides and near the base of the tentacles. The operculum has serrated

edges.

GENUS ^Nassa^

[Illustration:/Nassa trivittata/, showing the animal as if crawling.]

[Illustration: /Nassa trivittata./]

^N. trivittata^, ^N. obsoleta^. These are the two nassas of the

New England and New Jersey coasts. The first has a more northerly

range, extending to the Gulf of St. Lawrence; the other is not

usually found north of Cape Cod, but below that point as far as

Hatteras it is probably the commonest shell of the coast. It fairly

swarms in sheltered muddy reaches about low tide. Little pools left

by the tide on the Jersey flats are sometimes so crowded with /N.

obsoleta/ that for lack of room the animals crawl over one another.

/N. trivittata/ is more commonly taken at small depths in the

harbors, where it seems to live well upon all kinds of sea-bottom.

Probably they exist in great numbers along the southern shore of

Long Island, for the beaches are often lined with their dead and

worn shells. Over half the specimens thus found will have a little

round perforation upon some whorl, showing that they were victims

of some cannibalistic brother. The shells of the /Nassidæ/ have a

short, ovate aperture, with a short anterior canal. The inner lip

is smooth, and is usually coated over with a more or less heavy

[pg391] deposit of enamel. /N. trivittata/ is about one half to

seven tenths of an inch long, and is yellowish-white. A series of

revolving grooves cutting across a series of longitudinal lines

gives the shell a decussated or granulated appearance. The whorls

are somewhat shouldered at the sutures, and are white inside.

/N. obsoleta/ cannot be called a handsome shell by the most

enthusiastic collector. Its spire is usually eroded or completely

dissolved away. The color is blackish to olive, with the aperture

purplish-black. The columellar lip is arched, with a twist or

fold in its lower portion. It is decussated by crossing lines and

grooves, though not so conspicuously as /N. trivittata/; sutures

simple; length one half of an inch to one inch. Old specimens not

only become eroded, but are usually covered with vegetable mould,

and are not over-inspiring to the collector. They often live in

brackish water, and frequent all the inlets and marine flats

between Cape Cod and Hatteras. Below Hatteras both this and the

last-named species occur, though not so plentifully.

[Illustration: /Nassa obsoleta./]

^N. vibex.^ This ubiquitous little mollusk seems content in any

station, and swarms in all the sandy bays of Florida. It is a

busybody, always on the move, and its long siphon is constantly

vibrating. The shell is about one half an inch long and shining

white, with brown or reddish spots. There are prominent

longitudinal undulations and revolving lines upon the lower part of

the body-whorl. The anterior canal is deeply cut and very short;

the columellar lip arched, richly calloused, and often granulated

at its base. This is probably the first live shell the collector in

Florida will encounter. The animal is very graceful and prettily

marked in color. The terminal cirri on the foot form a notable

feature--a character belonging to the entire family.

[Illustration: /Nassa vibex./]

^N. fossata^, ^N. perpinguis^. On the California coast there are

the huge (for this genus) /N. fossata/ and the smaller but no less

interesting /N. perpinguis/, also ^N. tegula^ and ^N. mendica^.

/N. fossata/ grows to a length of one and a half to two inches.

When adult the lip is somewhat thickened, and the entire aperture

is bright orange. The color of the shell is ashen-gray, and it

is marked with spiral and transverse riblets which produce a

granulated surface, especially upon the upper whorls. The shell is

ribbed inside the mouth. A deep groove circles the anterior canal

at the base of the body-whorl. /N. perpinguis/ is an especially

graceful shell, smaller than the last-named and more finely

decussated and darker (brown) in color. It also has a deeply

channeled groove encircling the base of the body-whorl. It is

often banded in chestnut. Both these species occur in the southern

part of California only; /N. tegula/ and /N. mendica/ are of more

northern range. The former resembles the Floridian /N. vibex/. /N.

mendica/ is a slender shell three quarters of an inch long, with

prominent longitudinal ridges, and light brown in color, with a

white aperture. (Plate LXXIV.)

FAMILY ~BUCCINIDÆ~

From the number of subfamilies and genera included in this

exceedingly large and comprehensive family, it would almost [pg392]

seem that it has served as a sort of dumping-ground for various

groups of mollusks of uncertain biological affinities. Although the

family has recently been reduced by the removal of several large

families, it still remains a bulky one.

GENUS ^Buccinum^

The animal is described at some length on page 330. It has no

striking peculiarities. The siphon in /Buccinum/ is fairly long; the

eyes are placed about midway between the base and the end of the

tentacles. It is in general a conventional prosobranch animal. The

great majority of the members of this family have a boreal range and

are found widely distributed within the colder waters of the world.

^B. undatum.^ This is the most prominent representative of the

/Buccinidæ/ upon the North Atlantic shores of the United States.

It is an exceedingly common shell, ranging from Cape Cod to

Greenland. It is also found in England and Scotland, where it is

extensively used as food under the familiar name of "whelk." It

affects every kind of station and seems to be as much at home in

very considerable depths as about the low-tide mark. Upon the Maine

coast it may be found almost everywhere, just below low tide. If

none are in sight they may be attracted by putting a dead fish

in a basket and anchoring it near shore. The American whelk is

somewhat smaller than the British variety, although it attains a

length of full three inches. It has revolving ribs and longitudinal

oblique folds. A yellowish-brown, velvety epidermis covers the

entire shell. The lip is simple, and the shell is white or golden

yellow within. The columella is somewhat twisted; the operculum

is corneous, with a lateral nucleus. The variations in this shell

are so great as to have caused naturalists no little perplexity.

Specimens taken near large cities are apt to be defective. (Plate

I.)

[Illustration: /Buccinum undatum./]

GENUS ^Chrysodomus^

^C. decemcostatus.^ One of the most striking shells of our

northeast coast. As its name indicates, it is decorated with

(normally) ten costæ. [pg393] These are prominent revolving ribs

or keels upon the body-whorl, the upper one being the largest, the

others diminishing in size toward the base of the shell. Upon the

upper whorls but two of these circling keels appear. The lip is

plain, but somewhat modified by the termination of the ribs. The

columella is arched above; the canal produced (sometimes to the

left). The color without is dull ashen-white to horn; within, pure

white. The operculum is small, with a terminal nucleus. The animal

is the same as /Buccinum/. This species is not quite so common as

/B. undatum/, but it is often found associated with it. At Eastport

and Bar Harbor it is abundant just below low-water mark.

[Illustration: /Chrysodomus decemcostatus./]

GENUS ^Sipho^

[Illustration: /Sipho Stimpsoni./]

^S. Stimpsoni.^ One of the most graceful of the larger shells of

our eastern coast. It is almost identical with the /S. islandicus/

of northern European waters, and for a long time was considered to

be the same species. /S. Stimpsoni/ is not found south of Cape Cod,

except possibly in deep offshore stations. North of that point it

ranges to Newfoundland, but it has enjoyed the reputation of being

a rare shell and has been greatly prized by local collectors in

consequence. It is, in fact, not rare to any one who is provided

with a dredge and rope enough to enable him to use [pg394] it

effectively in from twenty to one hundred feet of water. The spire

is high and regular, with seven to eight slightly rounded whorls.

The suture is simple, and there are faint revolving grooves. The

epidermis is thick, horn-colored, and sometimes velvety; the lip

simple; and the anterior canal produced. The shell is pure white

within. The operculum is corneous, with a subterminal nucleus. The

animal is the same as /Buccinum/, but with small irregular specks

of black. This shell is found from three to five inches long.

[Illustration: /Sipho pygmæus./]

^S. pygmæus.^ This species has the same range as that of the

species just described, and often occurs associated with the young

of the latter. It may be distinguished from /S. Stimpsoni/ by the

greater number of whorls, the more prominent revolving ridges, and

the smaller aperture. The epidermis is drab-colored and strongly

corrugated, inclined to hirsute. The color of the shell is pure

white. Length one inch to one and a half inches. It is found from

low-tide mark to very considerable depths.

GENUS ^Siphonalia^

^S. kellettii.^ /Siphonalia/ is one of the Pacific genera of the

/Buccinidæ/, which finds its greatest development in Japanese

waters. One of these Japanese species, /S. kellettii/, is also

found in California. It has the typical animal of the /Buccinidæ/,

and a fusiform shell white to brownish in color, and three to five

inches in length. It is conspicuously marked upon the whorls by a

revolving series of large rounded knobs and indistinct revolving

grooves. The operculum is corneous, the nucleus subterminal. It is

found in shallow water to low-tide mark. (Plate LXXIV.)

GENUS ^Tritonidea^

^T. tincta.^ A Floridian species which ranges from Hatteras to

the West Indies, and finds its station near low-tide mark, upon

coralline rock or rough, stony bottom. It is about one inch in

length, is of a brownish horn-color, and has an oval aperture with

a crenulated outer lip and a deep anterior canal. An entering ridge

of white enamel at the top of the columellar lip forms, with one of

the teeth of the outer lip, a posterior canal. It is sculptured,

with revolving ridges and crossing longitudinal folds. The color

is bluish-white within the shell, touched with yellow about the

anterior canal and along the edge of the outer lip. (Plate LXXIV.)

FAMILY ~TURBINELLIDÆ~

GENUS /Fulgur/

Of the two genera of this family which occur in American waters,

/Fulgur/ may be taken as the most characteristic mollusk of the

American Atlantic fauna; that is to say, /Fulgur/ occurs only on

the American east coast. Its range is from Cape Cod to the West

Indies. The two Northern species are /F. carica/ and [pg395] /F.

canaliculata/, both of which are exceedingly common in sandy shore

stations from Cape Cod southward.

[Illustration: /Fulgur carica./]

^F. carica.^ The largest univalve north of Hatteras, most easily

recognized by its pear-shaped shell, with simple suture and

brilliant vermilion aperture. The anterior canal is long and

open; the columellar lip is twisted and arched, and the outer

lip is simple. There is a revolving row of nodes or spines of

various degrees of prominence upon the shoulder of the body-whorl,

continued on the spiral whorls just above the suture. The color

varies from ashen-gray to a dirty brown. In young specimens there

are stripes and bands of violaceous brown, and the shells are

striate within the aperture. The length of this shell is sometimes

nine inches.

^F. carica^ frequents almost any sort of bottom. In Long Island

Sound they are common on stony ground, but they do not attain

the maximum size and the high degree of aperture-coloration

characteristic of those taken along the New Jersey shore, on sandy

stations exposed to the surf. The string of curiously shaped

capsules containing the eggs of /Fulgur/ is shown in Plate I.

[Illustration: /Fulgur canaliculata./]

^F. canaliculata^ often occurs associated with the last. It does

not attain quite the same size, but specimens of both species

are, on the [pg396] average, about equal in cubic capacity. It

is pear-shaped, like /F. carica/, and has a long anterior canal;

but its distinguishing features are the flattened shoulder of the

whorls and the deeply channeled sutures. The epidermis is brown,

thick, and heavy. The color of the shell is whitish-gray, yellowish

within. It is found in the same places as /F. carica/, and is very

abundant at Atlantic City and along the entire New Jersey coast.

^F. perversa.^ A Floridian species, immediately recognizable by the

fact that it is sinistral; otherwise a description of the shell

would almost fit that of /F. carica/, except in the matter of the

color of the aperture, which in /F. perversa/ is brownish-white.

The brownish streaks upon the whorls, in young specimens, are

a very noticeable feature of this shell. The shoulders of the

whorls are rather flatter than in /F. carica/, but, unlike /F.

canaliculata/, the sutures are simple. The row of nodes or rounded

spines which encircles the body-whorl appears in the spire as nodes

just above the sutures. The animal is jet-black, and frequents

sandy flats, where, at low tide, it may be gathered in considerable

numbers, as it plows its way along, almost wholly concealed beneath

the sand. Large specimens measure quite a foot in length. In old

shells the color-markings are not so brilliant, the shells being a

dull, lusterless white. (Plate LXXV.)

^F. pyrum.^ Another Floridian species, much smaller than the last

(three to four inches), with a regular, pear-shaped outline, a long

anterior canal, a low spire, deeply channeled sutures, flattened

shoulders, and no spinous or nodose processes. It is ornamented

with revolving inconspicuous ribs or striæ, alternately larger,

and has a somewhat hirsute epidermis. The color is white, with

transverse broad yellowish or rusty lines; the color within the

aperture resembles that of the exterior color-lines. It is found on

sandy stations, in shallow water. (Plate LXXV.)

GENUS ^Melongena^

^M. corona.^ A Floridian species, named from the single or double

row of spinous processes upon the shoulder of the body-whorl and

the crenulated appearance of the spire caused by the continuations

of the triangular spines. The three apical whorls are not spinous.

There is also a row of hollow triangular spines obliquely

encircling the base of the shell. The epidermis is heavy, rough,

and brown; the aperture oval and large; the outer lip notched at

points where the spines commence; the anterior canal wide and

short; and the columella white and twisted, and banded within with

purplish-chestnut and white. The color without is drab in older

specimens, in young specimens chestnut banded with revolving striæ.

Length four inches. Found in shallow water. This active predaceous

animal must be the terror of the mollusks in Florida. With his

sharply toothed radula he is able to pierce even the ponderous

clam-shell, /Venus mercenaria/, variety /mortoni/, and devour the

soft fleshy parts within. No mollusk, save, perhaps, the vigorous

/Strombus pugilis/, can escape the attack of this highwayman.

(Plate LXXV.)

[Illustration: PLATE LXXV. Fulgur perversa. Melongena corona. Fulgur

pyrum.]

[Illustration: PLATE LXXVI. Fasciolaria gigantea, very much reduced.

Fasciolaria distans. Fasciolaria tulipa.]

[pg397]

FAMILY ~FASCIOLARIIDÆ~

This family comprises a number of genera of mollusks which have a

fusiform shell, with a long-drawn-out spire and a long anterior

canal. The animal is in no manner remarkable; no essential

differences are to be noted from the usual conventional type of

gasteropod mollusk, represented in the two families last described.

GENUS ^Fasciolaria^

This genus is of tropical range, and contains many species of shells

which are more or less conspicuous for their large size or their

beauty of form. Three species occur in Floridian waters, and all

of them may be taken about low-tide mark on the sandy flats which

are so characteristic of Florida bays and harbors. All of them are

sluggish animals which crawl very slowly along the bottom or bury

themselves almost wholly in the sand, leaving only the tip of the

spire projecting slightly above.

^F. gigantea.^ This is said to be the largest gasteropod shell

known. It often attains a length of sixteen inches, and specimens

are reported to have been found measuring no less than two feet.

This huge mollusk has a symmetrically fusiform shell, with whorls

obtusely ridged and armed with large rounded nodes. The aperture

is reddish-brown within. The anterior canal is long and open, and

there are three "plaits," or folds, about the columella. The outer

lip is more or less sinuate, the color is fleshy-white, and the

shell is covered with a thick yellowish or chestnut epidermis. The

animal is of a brilliant scarlet color. (Plate LXXVI.)

^F. tulipa.^ An exceedingly common species of Floridian waters,

which may justly be classed among the "show shells" of the American

Atlantic fauna. It has a typically symmetrical, fusiform shape,

with gracefully rounded whorls, and is spirally but not deeply

grooved. The sutures are crenulated; the anterior canal is long;

there are three entering folds upon the columella; and the outer

lip is simple. The scheme of coloration is variable, but there are

two chief patterns, which are usually followed, though they often

are considerably modified. One is a light-bluish body, variegated

with chestnut or olive blotches, which are more extensive upon

the spire than upon the body-whorl; the other is a pinkish body,

encircled with revolving black lines. The specimens of /F. tulipa/,

which are found so abundantly in the shallow bays and estuaries of

the Florida coast, are, for some reason, never brightly colored, as

are those taken in the open sea. The length is about four to six

inches. (Plate LXXVI.)

^F. distans.^ A form almost identical with that last described. It

is much smaller, varying from two to three inches in length, lacks

the crenulations of the sutures, and is perfectly smooth, save for

a few spiral ridges about the base. The color is bluish-white, with

clouded longitudinal [pg398] streaks of olive. Encircling the

shell are from four to seven black lines. (Plate LXXVI.)

These three species of /Fasciolaria/ often occur associated upon

sand-banks which are exposed at unusually low tides. It requires

some force to dislodge the large /F. gigantea/ from its bed of

sand. When the apex is discovered projecting an inch or less from

the bottom, the collector must scrape away the sand down to the

body-whorl, and then secure a good hold upon the spire and pull

hard. The stupid animal will not at once withdraw into his shell,

but will hang protruded from the aperture like a great piece of

vividly red meat. To extract any of these larger fasciolarias from

its shell, it is necessary to boil it for ten or fifteen minutes.

Large specimens of /F. gigantea/ should remain in the pot half an

hour. The heavy corneous epidermis of /F. gigantea/ will dry and

crumble away unless it is rubbed with vaseline about once a year.

FAMILY ~VOLUTIDÆ~

GENUS ^Voluta^

[Illustration: /Voluta junonia./]

The =Volutidæ=, like the cowries, are "aristocratic" shells. As was

stated above, there are many collectors who have become so fascinated

by the shells of a few of these "first families of the /Mollusca/"

that they make great efforts and spend no small sums in seeking to

complete their cabinet series of the rare and more beautiful forms.

The /Volutidæ/ certainly have very beautiful shells, and they are for

the most part exceedingly rare. The reason of their rarity has no

doubt something to do with their habits. They are probably largely

dwellers upon rocky ground, where the dredge cannot reach them.

There is but one species of /Voluta/ upon the American coasts which

is available to the shore-collector, and this is the well-known and

much-sought-after ^V. junonia^. The animal of /Voluta/ has a very

broad foot, and a head curiously divided into two lobes, upon which

are placed sessile eyes. A remarkable feature of the genus is the

lack of an operculum. [pg399]

^V. junonia.^ This volute has never been taken alive in shallow

water near the shore, but is occasionally found cast upon the

beach after violent storms. Sanibel Island is the best locality.

/V. junonia/ has an obtuse apex, a long aperture, and a shell

from three to three and a half inches in length. The color is

cream-white, painted with rows of large deep-red spots. In his

"American Marine Shells," published nearly thirty years ago, Mr.

Tryon says: "This is the most rare and valuable American marine

shell; specimens in good condition sell for from fifty to one

hundred dollars." A good specimen is probably not worth so much

to-day as when Mr. Tryon wrote, but it is at least worth a careful

survey of a Floridian beach after a storm.

FAMILY ~MARGINELLIDÆ~

GENUS ^Marginella^

This is a family of exquisite little shells. In point of beauty they

would rival the volutes were they not so much handicapped by their

small size. The largest /Marginella/ is not more than an inch and a

half in length, while the great majority of its two hundred tropical

species do not exceed one half an inch. The animal is very similar

to that of /Voluta/; indeed, the marginellas were until recently

included in the /Volutidæ/. The shell is also suggestive of /Voluta/.

It is porcelanous, highly polished, and shining like all shells

which are covered by a portion of the mantle when the animal is

extended. Forty-seven species of /Marginella/ are recorded from the

Atlantic coast of the United States. The marginellas frequent sandy

or muddy sheltered spots, and may be collected between tide-marks.

In California there are several species, which are so minute that it

seems hardly worth while to attempt a description of them. They are

white and very inconspicuous little shells. One is tempted, however,

to speak of some of the fine marginellas of the Bahamas. The animals

are quite as beautifully marked as the shells themselves, while the

shell of one species is used in jewelry on account of its pearly

luster suffused with the most delicate pink.

^M. apicina.^ The most abundant Floridian species of this genus. It

is not more than one third of an inch long, with a depressed spire,

a large body-whorl, a long aperture nearly equaling the entire

length of the shell, a thickened outer lip, and four very prominent

plaits on the columella. The surface is smooth. The white, enlarged

outer lip is glazed or highly polished, and bluish or brown in

color, with red spots. (Plate LXXVII.) [pg400]

FAMILY ~OLIVIDÆ~

GENUS ^Oliva^

The genus /Oliva/ is one of the favorites among collectors. It

comprises smooth, highly polished, porcelanous, and oval shells

with a deeply notched, long, narrow aperture. The columellar lip is

usually heavily calloused and ornamented with oblique folds. The

animal's foot is very large, and extends laterally into lobes which

curve back over the shell. In front the propodium is very large,

forming, as in /Natica/ and /Polynices/, a sort of plow. The mantle

lobes almost cover the shell when extended.

^O. literata.^ The only American example out of some sixty known

species. It is found in great abundance in sandy tide-pools along

the west Florida shores. It ranges from Hatteras to the West

Indies, and may be looked for in stations similar to those of the

naticas. It is exceedingly active, crawling rapidly over the sand

or burying itself very quickly out of sight, and is carnivorous.

The shell is highly polished, about two inches long, and pale

yellowish-white in color, covered with longitudinal, angulated,

or zigzag lines of chestnut. The spire is short, the sutures

channeled, and the columella calloused with white enamel, and

obliquely striated. (Plate LXXVII.)

GENUS ^Olivella^

The genus /Olivella/ resembles /Oliva/ very closely in conchological

characters, but the shells are, with few exceptions, exceedingly

small, and usually have a somewhat more elongated spire than is the

case in the genus /Oliva/ proper. The animal of /Olivella/ seems to

be a degenerate, for it possesses neither tentacles nor eyes. In

habit and station it resembles /Oliva/.

^O. mutica.^ In Floridian waters this species is exceedingly

common. It is not more than one fifth of an inch long, is highly

polished and shining, and yellowish-white in color, with revolving

pale rufous bands. It has the typical oliva-shape.

[Illustration: PLATE LXXVII. 1, Marginella apicina, enlarged.

3, Olivella biplicata, enlarged. 2, Oliva literata. 4, Conus

floridanus. 5, Cancellaria reticulata.]

^O. biplicata.^ A Californian species of considerable interest, the

largest of the olivellas. It was evidently used by the aborigines

as wampum or as ornaments, for a great many specimens are found

among buried Indian relics. This species is about the size and

shape of an olive. The spire is short, though longer than the

typical /Oliva/ spire, the shell is smooth and highly polished, and

the columella is thickly calloused, and has two entering folds near

the base. The color is creamy-white to dove-color, with a purple

sheen over all, and purple markings [pg401] about the base.

Professor Keep speaks of the vast numbers of these olivellas on

sandy stations along the Pacific coast. Having found a place where

a "little stream of water was oozing out from the bank of sand,"

he proceeded to dig with a hoe. "I found them [/O. biplicata/] by

the hundreds," he continues, "and I had gathered about a thousand

before the tide came in. They seemed to lie in groups just under

the surface of the sand, yet wholly concealed from sight." (Plate

LXXVII.)

^O. boetica.^ A much smaller Pacific form, with a higher tapering

spire. It is brown to bluish in color, and often has yellowish

stripes. It is polished and shining. Found in sandy stations.

FAMILY ~CONIDÆ~

GENUS ^Conus^

This is a comprehensive family of several highly diversified genera.

Its most prominent genus is /Conus/, a name which indicates the

principal feature of the shell, for it is almost an exact cone in

shape. /Conus/, along with /Voluta/ and /Cypræa/, is entitled to the

honor of being considered an aristocrat among mollusks. There are

about three hundred and fifty species known, mostly tropical and

Indo-Pacific in distribution. The shells have many points of beauty

and are often of very high coloration and eccentric markings. Some of

the rarer forms are famous in conchological annals for the enormous

prices which they have commanded. The rare and beautiful /Conus

gloria-maris/ once brought £43 ($215) at an auction sale in London.

In all shells of /Conus/ there is a notch at the upper edge of the

aperture for the accommodation of a posterior canal. In some other

genera of this family this notch becomes a more prominent feature.

The animal has a well-developed foot, a retractile proboscis, eyes

situated upon the tentacles, and a fairly long siphon. Upon the

under surface of the foot is a conspicuous pore, which opens into a

water-vascular system of the foot. /Conus/ is accused of having a

poison-gland connected with the radula and of having shown vicious

traits when captured. The animals are shy, and remain most of the

time in hiding, while their pretty shells during life are generally

rendered obscure by a dull, colorless epidermis. There are but few

species of /Conus/ upon the Atlantic shores of the United States, and

these are confined to the warmer waters of Florida and the Gulf of

Mexico. [pg402]

^C. floridanus.^ A not unusual shell in shallow-water stations

throughout the Florida coast. It has almost the exact outlines of

a cone. The flattened shoulder is marked off by an acute carina;

the spire is low, but many-whorled and pagoda-like; the aperture is

long and narrow, and the lip is simple. The coloring is yellowish,

banded on a creamy-white background, or dotted in circular rows.

Length two inches. (Plate LXXVII.)

^C. pealii.^ One of the smallest species of this genus, its length

never exceeding one half of an inch, whereas the majority of the

cones are over two inches in length, and many of them rank as large

shells. This little Floridian species is regularly cone-shaped,

with carinated whorls, thin outer lip, and pagoda-like, low spire.

The color is reddish-brown with sky-blue spots, or bluish-brown

with lighter spots. There are encircling grooves about the base of

the shell.

FAMILY ~CANCELLARIIDÆ~

GENUS ^Cancellaria^

The last family of the /Gasteropoda/ to be considered is the

/Cancellariidæ/, which has but one genus, ^Cancellaria^. There are

several species upon the east coast belonging to deeper-water zones,

but one well-known species, ^C. reticulata^, is very common on shore

stations from Hatteras south. The shell is oblong and solid, with a

moderate spire, and whorls slightly flattened below the sutures, and

is very roughly granulated or reticulated. The aperture is narrowly

ovate, and is ribbed inside. The columella has two very strong and

prominent plaits. The color is white, banded and variegated with

reddish-brown. Length an inch or more. (Plate LXXVII.)

CLASS =SCAPHOPODA=

FAMILY ~DENTALIDÆ~

[Illustration: /Entalis striolata./]

In nearly all collections of shells from the northeast coast of the

United States are certain specimens about one to one and a half

inches long, pure white, and shaped very much like an elephant's

tusk. They are round, hollow tubes, slightly curved, of larger

diameter at one end than at the other, and with an opening at either

end. There are two very common species of these tooth shells upon

the New England coast, [pg403] ^Dentalium dentale^ and ^Entalis

striolata^. The first has a simple round hole at the smaller end of

the shell, and is faintly marked by longitudinal striæ; the other is

a smooth shell which has a notch-like fissure on the margin of the

apical perforation. Neither of these species is, strictly speaking, a

littoral form, for all the /Dentalidæ/ range into deep water, many of

them living only in the profounder depths of the ocean. But these two

species are exceedingly common in the New England coastal waters, at

very moderate depths, and may sometimes be found upon the beach cast

up by storms. They live buried in the mud, and feed upon infusorians

and all manner of microscopic organisms.

Upon the west coast ^Dentalium pretiosum^ is very abundant north of

California. It is almost like the east-coast /Dentalium/, but is more

slender. The Indians used to gather these shells and string them

together upon long threads to be carried about and used as money.

In California occurs ^Dentalium hexagonum^, a very delicate little

species with a slightly angulated shell.

[Illustration: /Dentalium/, as seen in longitudinal section (except

the foot): /S/, shell; /Mt/, mantle; /Sm/, shell muscle; /Mh/,

mantle-cavity; /F/, foot; /Mk/, cephalic prominence or oral cone;

/T/, captacula; /R/, radula; /D/, intestine; /L/, liver; /Af/, anus;

/G/, cerebral ganglion; /N/, kidney; /Ge/, generative gland.]

The animal of the /Dentalidæ/ is remarkable, and easily merits the

rank of a separate molluscan class. It has no head, no tentacles,

no eyes, no heart, and no gills. It is a mollusk because it has a

mantle, a foot, and a radula. Its position, therefore, is between the

/Gasteropoda/, which it resembles in its univalve shell and radula,

and the /Pelecypoda/, to which it is related by the pointed foot and

the absence of head and tentacles, and also by the symmetry which

pervades its organization.

Upon either side of the mouth, just beneath the flap of the mantle,

are bunches of ciliated, contractile filaments (/captacula/),

flattened at the end, which are supposed to be breathing-organs, and

are perhaps exserted for the purpose of catching food. [pg404]

The entire absence of such important organs as the heart and gills,

together with the fact that they are undoubted mollusks, would

indicate that the /Scaphopoda/ are very degenerate animals. The

circulatory and respiratory system of mollusks is typically of a high

order.

A great many specimens of the /Dentalidæ/ dredged in New England

waters are dead shells, occupied by a worm which seals up the larger

opening, leaving only a small aperture through which it protrudes its

long white body. These must not mislead the collector into a vain

search for a mantle and other molluscan characteristics of anatomy.

Some of the larger species of /Dentalium/ from deep-sea stations are

four to five inches in length. [pg405]

TABLE OF THE COMMONER NORTH AMERICAN PELECYPODS DESCRIBED IN THIS

CHAPTER

Class =PELECYPODA=

Order =PROTOBRANCHIATA=

Families Genera Species

NUCULIDÆ ^Nucula^ ^N. proxima^

^Leda^ ^L. tenuisulcata^

^Yoldia^ ^Y. limatula^

^Y. thraciæformis^

^Y. sapotilla^

SOLENOMYIDÆ ^Solenomya^ ^S. velum^

^S. borealis^

Order =FILIBRANCHIATA=

ANOMIIDÆ ^Anomia^ ^A. simplex^

^A. aculeata^

^A. lampe^

^Placunanomia^ ^P. macrochisma^

ARCIDÆ ^Arca^ ^A. ponderosa^

^A. noæ^

^A. pexata^

MYTILIDÆ ^Mytilus^ ^M. edulis^

^M. hamatus^

^M. californicus^

^Modiola^ ^M. modiolus^

^M. plicatula^

^M. tulipa^

^M. recta^

Order =PSEUDOLAMELLIBRANCHIATA=

AVICULIDÆ ^Avicula^ ^A. atlantica^

^Pinna^ ^P. muricata^

^P. seminuda^

^Perna^ ^P. ephippium^

OSTREIDÆ ^Ostrea^ ^O. virginica^

^O. frons^

^O. lurida^

PECTINIDÆ ^Pecten^ ^P. magellanicus^

^P. irradians^

^P. dislocatus^

^P. islandicus^

^P. æquisulcatus^

^P. hastatus^

Order =EULAMELLIBRANCHIATA=

CARDITIDÆ ^Cardita^ ^C. borealis^

^C. floridana^

ASTARTIDÆ ^Astarte^ ^A. castanea^

^A. undata^

CYPRINIDÆ ^Arctica^ ^A. islandica^

LUCINIDÆ ^Lucina^ ^L. tigrina^

^L. floridana^

^L. pennsylvanica^

^L. dentata^

^L. californica^

^L. nuttallii^

^Loripes^ ^L. edentula^

TELLINIDÆ ^Tellina^ ^T. radiata^

^T. alternata^

^T. bodegensis^

^T. tenera^

^Macoma^ ^M. secta^

^M. nasuta^

^M. baltica^

^M. proxima^

^M. tenta^

DONACIDÆ ^Donax^ ^D. variabilis^

^D. californicus^

MACTRIDÆ ^Mactra^ ^M. solidissima^

^M. similis^

^M. ovalis^

^M. lateralis^

^R[oe]ta^ ^R. canaliculata^

VENERIDÆ ^Venus^ ^V. mercenaria^

Var. ^mortoni^

^V. cancellata^

^Cytherea^ ^C. (Callista) gigantea^

^C. (Callista) maculata^

^Dosinia^ ^D. discus^

^D. elegans^

^Tivela^ ^T. crassatelloides^

^Tapes^ ^T. staminea^

^T. laciniata^

^Chione^ ^C. succincta^

^C. fluctifraga^

^C. simillima^

^Saxidomus^ ^S. nuttallii^

PETRICOLIDÆ ^Petricola^ ^P. pholadiformis^

^P. carditoides^

CARDIIDÆ ^Cardium^ ^C. magnum^

^C. isocardia^

^C. lævigatum^

^C. serratum^

^C. mortoni^

^C. substriatum^

^C. corbis^

^C. quadrigenarium^

^C. elatum^

^C. islandicum^

^C. pinnulatum^

MYIDÆ ^Mya^ ^M. arenaria^

SOLENIDÆ ^Ensis^ ^E. directus^

^Solen^ ^S. viridis^

^S. sicarius^

^S. rosaceus^

^Tagelus^ ^T. gibbus^

GLYCIMERIDÆ ^Glycimeris^ ^G. generosa^

PHOLADIDÆ ^Pholas^ ^P. costata^

^P. truncata^

^P. californica^

^Zirph[oe]a^ ^Z. crispata^

TEREDINIDÆ ^Teredo^ ^T. navalis^

PANDORIDÆ ^Pandora^ ^P. trilineata^

[pg408]

[Illustration: Anatomy of a pelecypod, /Anodonta cygnea/. The animal

with most of the left mantle lobe removed. /a/, excretory opening;

/a. ad./, anterior adductor muscle; /a. r./, anterior retractor

muscle; /au./, left auricle; /d. p. a./, dorsal pallial aperture;

/ex. sph./, exhalant siphon; /ft./, foot; /in. sph./, inhalant

siphon; /kd./, kidney; /l. ext. gl./, left external gill; /l. ext.

plp./, left external labial palp; /l. int. gl./, left internal gill;

/l. int. plp./, left internal labial palp; /l. m./, cut edge of left

mantle lobe; /mth./, mouth; /p. ad./, posterior adductor muscle;

/pc./, pericardium; /p. r./, posterior retractor muscle; /prc./,

protractor muscle; /rct./, rectum; /r. m./, right mantle lobe; /v/,

ventricle; /v. m./, visceral mass.]

[Illustration: Anatomy of a pelecypod, /Anodonta cygnea/.

Dissection from the left side. /a/, excretory opening; /a. ad./,

anterior adductor muscle; /a. ao./, anterior aorta; /a. v. ap./,

auriculo-ventricular aperture; /bl./, urinary bladder; /c. pl. gn./,

cerebropleural ganglion; /d. d./, duct of digestive gland; /d.

gl./, digestive gland; /d. p. a./, dorsal pallial aperture; /ex.

sph./, exhalant siphon; /ft./, foot; /g. ap./, genital aperture;

/gon./, gonad; /gul./, gullet; /i. l. j./, interlamellar junction;

/in. sph./, inhalant siphon; /int./, intestine; /kd./, kidney; /m/,

mantle; /mth./, mouth; /p. ao./, posterior aorta; /p. ad./, posterior

adductor muscle; /pc./, pericardium; /pd. gn./, pedal ganglion; /r.

ap./, renal aperture; /r. au./, right auricle; /rct./, rectum; /r. p.

a./, reno-pericardial aperture; /st./, stomach; /ty./, typhlosole;

/v./, ventricle; /v. gn./, visceral ganglion; /w. t./, water-tubes.]

[pg409]

CLASS =PELECYPODA=

This is a large and important class of the /Mollusca/, comprising an

extensive group of animals, which vary widely in structure. Next to

the /Gasteropoda/, it is the largest class of the phylum in number

of genera and species. The name indicates a "hatchet-shaped" foot,

but in many cases it is a misnomer. /Acephala/, meaning "without a

head," is also employed for this class, and is, perhaps, a better

term. /Lamellibranchiata/, referring to the type of gills prevalent

throughout the division, is another name often used. The popular

name "bivalves" is an altogether correct one, for all the animals

of this class have two shells. To the /Pelecypoda/ belong the

oysters, clams, scallops, mussels, and, in short, all the /bivalve/

mollusks (the word "valve" meaning "shell"). The organization of a

pelecypod is entirely similar to that of a gasteropod or a chiton

in its fundamental or essential plan, but it differs widely from

both in matters of detail. If the student will keep in mind the

general principles of gasteropod or the amphineuran structure when

he dissects his first pelecypod, he will quickly see that the latter

is about the same as a chiton would be were it folded over from a

longitudinal median line as axis along its back, so that the opposite

mantle-edges would meet, and its various shell-plates would unite

upon either side into a single valve; or it is very like a gasteropod

made symmetrical, and covered upon its two sides by separate shells

instead of covered over its top by one shell. The loss of head,

eyes, and tentacles, the substitution of labial palps, the extension

and greater development of the gills, the modification of the foot

and mantle, and the presence of certain special glands in the

/Pelecypoda/ become mere matters of anatomical detail. [pg410]

Any large clam will serve for dissection. In the neighborhood of

New York the edible species known as the "Little Neck" clam (/Venus

mercenaria/), or the larger /Mactra/ of the sandy shores, will

answer the purpose very well. In Florida, /Callista/, /Venus/, and

/Cardium/ are all available. On the west coast the large, heavy

/Tivela crassatelloides/ is probably the best subject. The oyster

(/Ostrea/) is a degenerate type; and the scallops (/Pecten/) and the

mussels (/Mytilus/ and /Modiola/) have certain special modifications

of their organs which might prove confusing, so these genera are not

recommended for dissection and study at first.

Boiling is apt to shrivel and distort the soft, fleshy animal of

the bivalves, and it is far better to examine a fresh specimen. The

surest way of opening a clam without injuring the animal is to break

one of the shells by sharp taps of a hammer, using great care not

to lacerate the body within by a too vigorous assault. Pick off the

broken pieces after having separated them carefully with a knife from

the mantle margin, to which they cling, and after having cut through

the tough adductor muscles as close to the shell as possible. The

subject for anatomical study is then prepared "upon the half-shell."

THE MANTLE

The mantle is generally very thin, often a fleshy film of the finest

tissue, and adheres to the inner side of each valve. The outer rim

of the mantle is thickened and free, i.e., is not attached to the

shell. This free portion is capable of slight extension beyond the

margin of the shell when the valves are opened and the animal is off

guard. In many genera the mantle edge is highly ornate, being waved,

crenulated, or fluted, or is beset with several rows of papillæ, and

is often richly colored. Mr. Hickson, a naturalist, who traveled in

Celebes, says that the brilliant coloring of the mantle margins of

mollusks contributed largely to the extraordinary color-effects upon

the coral reefs.

It will be seen that the mantle entirely incloses the animal at the

back and sides, just as the cover of a book incloses the pages or

printed portion. At the posterior end of the animal there is usually

a point--or perhaps two points--at which the flaps of [pg411] the

mantle lobes unite in order to form two openings. These openings are

called the siphons.

[Illustration: 1, /Solecurtus strigillatus/, showing partly united

siphons covered with leathery integument: /s. af./, incurrent siphon;

/s. ef./, excurrent siphon; /SS/, the two uniting. 2, /Cardium

edule/, showing partly united siphons with papillaceous orifices:

/A/, excurrent; /B/, incurrent siphon; /F/, foot. 3, /Scrobicularia

piperata/, in its natural position in the sand, showing very long

tubular siphons: /A/, excurrent siphon; /B/, incurrent siphon.]

SIPHONS

In some cases the mantle lobes do not actually unite to form regular

siphonal openings, but in life the free mantle-edges have a way

of adjusting themselves posteriorly to form /functional siphons/

without actually coalescing. Usually, however, the mantle flaps

not only unite posteriorly to form true siphons, but are capable

at that point of varying degrees of protrusion from the shell, and

when extended the siphons appear as two tubes. In some genera these

siphonal tubes are very long; in others they are fastened together

and surrounded by a tough, leathery integument, [pg412] which, like

the siphons proper, is only an extended portion of the mantle-edge.

The orifices of the siphons are generally papillaceous. These two

siphons (for there are always two if there are any at all) are the

/anal/ or excurrent (upper) and the /branchial/ or incurrent siphon.

The function of the latter is to draw in the pure water to bathe the

gills and to furnish food, while the office of the former is to eject

waste materials and the water which has already passed over the gills.

[Illustration: Diagram illustrating the various degrees of union of

the mantle lobes: A, mantle completely open; B, rudiments of siphons,

mantle still completely open; C, mantle closed at one point; D,

mantle closed at two points, with complete formation of siphonal

apertures; E, development of siphons, ventral closure more extended;

F, mantle closed at three points, with fourth orifice; /f/, foot; /s.

a./, /s. b./, anal and branchial siphons; 1, 2, 3, first, second, and

third points of closure of mantle; /b. o./, byssal aperture.]

MANTLE FUSION

Besides the points of juncture where the mantle-edges unite to form

the siphons, the coalescence of the two mantle lobes may be extended,

and they may become further united and fused together at other

points. Indeed, the fusion of the mantle-edges may become almost

complete; but it always leaves the siphonal openings and a third

opening through which the foot may be extended. This opening for

the foot is called the /pedal opening/, or orifice. In such cases,

therefore, the mantle becomes much like a bag or sac. The degree of

fusion of the mantle-edges appears to correspond closely with certain

changes in the organization of the animal, and this feature must be

regarded as a very important character. [pg413]

The figures on pages 411, 412, and 413 show the degrees of mantle

fusion in various groups from the open to the almost wholly closed

types. One (A, page 413) gives an example of very large siphons

united together and protected by the tough, leathery integument. To

the right of this cut may be seen the foot projecting from the pedal

opening in the mantle. Another gives the two siphons of /Cardium/,

the lower or branchial one being the longer. The mantle-edges below

are fluted, and a large foot projects forward. Another shows two

siphons of /Scrobicularia/, of the free and greatly extended type.

Fig. B (page 413) illustrates the ventral portion of a pelecypod,

which shows very well the most advanced type of mantle fusion.

Besides the siphonal openings at the end of the long projection to

the left, the only other opening is the very small orifice marked

"2," for the accommodation of a small, insignificant foot. In the

other figures different degrees of mantle fusion are indicated.

[Illustration: A: 1, incurrent siphon; 2, excurrent siphon; 3, foot.

B: 1, siphons; 2, pedal opening.]

Before removing the mantle from one side of the specimen to be

examined, note the two strong muscles which are at either end of the

body. These are the /anterior/ and /posterior adductor/ muscles,

their office being to hold the valves tightly shut. They are of great

strength, as any one may prove to his satisfaction by attempting

to open a clam. Through a long series of forms these two muscles

approach each other in position, and in the scallops and the oysters

there is but one adductor muscle, occupying a central position.

Morphologically it is the survival of the posterior adductor.

THE BRANCHIÆ OR GILLS

Removing carefully the thin, fleshy mantle, the gills are exposed

to view--that is, of course, the gills of that side of the [pg414]

animal, for there are two sets, one upon each side of the body, or

visceral mass, and lying between the body proper and the mantle

folds. Each set consists of two plate-like bodies with a texture of

reticulated or basketwork appearance. Thus there are the inner and

outer right gills and the inner and outer left gills. If one gill is

removed and carefully examined it will itself probably be found to

be double, consisting of many filaments placed side by side and then

doubled back like a row of hairpins, the filaments being united by

interciliary processes, or by vascular channels together with more or

less dense connective tissue.

The modifications of the pelecypod gills are difficult to follow,

but the principle upon which they perform their duties is the same

in all cases. The gill-filaments are all connected with a long vein,

and, being hollow, admit the blood, which is aërated by close contact

with the water and is then returned to another vein in immediate

connection with the auricles of the heart. There is another function

accomplished by the gills, which in some families seems to be quite

as important as their respiratory one, namely, the office of giving

lodgment to the ova while in process of development before hatching.

At certain seasons the gills of a number of pelecypod genera become

literally filled with eggs; sometimes this curious phenomenon extends

to the mantle itself, and more or less to the entire surface of the

animal. The eggs are first regularly ejected from the genital ducts

and find lodgment upon the body-surface, but usually only upon the

gills, where they remain as in a brood-pouch between the lamellæ of

the inner and outer gills. When the eggs hatch, the free-swimming

young escape from the mantle cavity. Probably not more than one

individual in a million ever reaches maturity.

The figure on page 408 shows the mantle removed, exhibiting the

gills, the foot, the labial palps, and the pericardium, inside of

which is the heart. Removing the gills, we find exposed the body, or

visceral mass, which, as in the /Gasteropoda/, is thickened below

into the foot. A longitudinal section is shown on page 408, the

visceral mass being sliced almost through the middle; a portion of

the gills of the farther side shows below. [pg415]

THE FOOT

The foot undergoes great variation, from a strong, powerful organ

capable of forcing its way through heavy gravelly bottom or burrowing

deeply into the sand or mud, to the merest trace of a pedal organ.

In the oyster the foot has become almost entirely atrophied; the

stationary life led by the animal renders such an organ quite

unnecessary. Excepting in a few families, the pelecypod foot is

well developed. In a number of genera the foot contains a gland

for the secretion of long silk-like or horn-like fibers, which

are collectively called a /byssus/. The use of a byssus is for

attachment to any object to effect a temporary or permanent lodgment.

The accompanying cut shows /Mytilus edulis/, a common east-coast

pelecypod, attached by its byssus to a piece of wood. Most bivalves

having a strong byssus exhibit a feeble development of the foot;

nearly all bivalves, however, show traces, sometimes only in the

embryo, of a byssal gland.

[Illustration: /Mytilus edulis/, attached by its byssus (/By/) to a

piece of wood: /F/, foot; /S/, excurrent siphon, the branchial siphon

being below it and not closed.]

[Illustration: /Pecten opercularis/, showing the ocelli, or eyes, on

the two edges of the mantle.]

The visceral mass contains the liver, the exceedingly large

generative glands, the kidneys, etc., and through all this soft

whitish or reddish mass the alimentary canal wanders about in a

tortuous fashion, finally passing through the pericardium and the

ventricle of the heart, and terminating just over and back of the

posterior adductor muscle. [pg416]

The pelecypods have no head or tentacles, but the place of the latter

is taken by two pairs of triangular flaps upon either side of the

mouth. These are called the /labial palps/, and they no doubt operate

by means of their ciliated surface to keep in motion the current of

water over the gills and to the mouth.

As a rule, pelecypods have no eyes, but when eyes are present they

are situated upon the edge of the mantle. The eyes are not highly

developed organs, but they nevertheless appear to be very sensitive

to light, for the bivalves which are so endowed will, when kept in

aquaria, instantly close their shells when the shadow of a fish

passes over them.

The heart lies in the pericardium and is situated dorsally, just in

front of the posterior adductor muscle. It has a median ventricle

and two lateral auricles, each connected with the branchiæ upon

its respective side. It seems a curious economy that passes the

intestine through the ventricle, but this is the case in the great

majority of pelecypod genera. The vascular system is closed and

is of a high order. It is probable that "breathing" takes place

upon the inner mantle surfaces as well as in the gills themselves;

for these surfaces are crowded with excessively fine and delicate

capillaries, which bring the blood very near to the water. This power

of "breathing by the skin" is quite characteristic of the /Mollusca/

in general.

Having once familiarized one's self with the more prominent features

of pelecypod organization, it becomes very interesting to examine

anatomically every new form that is captured. Surprises are always in

store, and sometimes the peculiar juxtaposition and relative sizes of

the organs are a trifle confusing; but, upon the whole, the bivalve

organization is simple and lends itself far more readily than does

that of the gasteropods to satisfactory examination. Some of the more

striking anatomical peculiarities are reserved for mention in the

notes upon the various genera and species common upon our shores.

THE PELECYPOD SHELL

As has been seen, the testaceous covering of the /Pelecypoda/

consists of two valves or shells which fit more or less closely

and [pg417] firmly together and are placed one upon either side of

the animal. The two valves are always held together tightly along a

dorsal margin by a "hinge ligament," an exceedingly tough, leathery

substance, and they are usually secured the more firmly by a system

of interlocking teeth, which project from the hinge. The opening and

shutting of the valves is controlled by the adductor muscles of the

animal, by the /ligament/ which binds the valves together, and by

the /cartilage/, an elastic pad of rubber-like appearance which is

lodged just within the hinge, and is compressed when the valves are

closed together. Thus, when the valves are closed, there is always a

strain upon the adductor to overcome the elastic resistance of the

cartilage. When a pelecypod dies and the pull of the adductor muscles

is released, the valves gape open.

[Illustration: The interior characteristics of a pelecypod shell.

Left valve of /Venus gnidia/: /A/, anterior, /B/, posterior, /C/,

dorsal, /D/, ventral margin; /AB/, length, /CD/, breadth of shell;

/a. m./, anterior, /p. m./, posterior impressions of adductor muscle;

/p/, pallial line; /p. s./, pallial sinus; /l/, ligament; /lu./,

lunule; /u/, umbo; /c/, cardinal teeth; /a. l./, anterior lateral

tooth; /p. l./, posterior lateral tooth.]

The summit or apex of the valve is called the /umbo/, or /beak/. It

is usually twisted to some extent, and in certain forms develops a

suggestive spiral figure. The beaks of the valves are the points

where the shell-growth begins, the secretion of calcareous matter

being made by the mantle margin and deposited about the edges of the

valves; the growth is therefore constantly away from the umbones.

The umbones usually point forward. In many species they touch each

other over the hinge-margin or approximate very closely; in other

species the hinge-margin is very wide and the beaks are comparatively

far apart. The hinge-margin, lying adjacent to the umbones, is known

as the /dorsal margin/ of the shell, in contradistinction to the

/ventral margin/, opposite the umbones. The /anterior margin/ is the

front edge and the /posterior margin/ the hinder edge of the shells,

through which the siphons may project.

When the umbones are about central in respect to the posterior

[pg418] and anterior margins, the shells are said to be

/equilateral/. When the two valves are almost exactly alike in size

and shape they are called /equivalve/.

In many forms there is a heart-shaped space upon the dorsal margin

of the closed valves forward of the umbones, called the /lunule/.

Similarly placed back of the umbones is sometimes a more or less

clearly defined space called the /escutcheon/. The outer surface

of bivalve shells admits of infinite variety of sculpturing and

ornamentation, ranging from a perfectly smooth to a heavily ribbed,

nodose, spinous, or deeply decussated surface. The color-markings are

often brilliant and eccentric.

The right and left valves may be distinguished by remembering that

the siphons are always posterior, and that the umbones usually point

forward.

The hinge of bivalve shells undergoes many variations in the

different genera. The simplest type is a smooth edentate surface

where the two valves meet and are held together only by the strong

ligament. Generally, however, there is a system of interlocking

teeth, those in the center of the hinge being the /cardinals/ and

those upon either side the /laterals/. In some forms there are rows

of fine comb-like teeth along the hinge-margin, with no distinction

between cardinals and laterals.

The object of these hinge-teeth is at once obvious, for they give a

rigidity and increased strength to the entire mechanism, especially

when closed. There is occasionally a saucer-shaped plate or platform

just under the cardinal teeth and within the shell, called the

/fossette/. Upon this rests the internal elastic cartilage.

Upon the smooth interior surfaces of the valves are always certain

markings, which correspond to anatomical features of the animal and

are consequently of considerable importance in the determination

of the systematic position of the specimen. First, the well-marked

impressions left by the adductor muscles will be noted; then a more

or less distinct line which, describing roughly a circle, connects

the two muscle scars. This line represents the points at which the

mantle became detached from the shell. In other words, all the space

within this /pallial line/ (barring the [pg419] muscle scars) was,

in life, covered by the mantle, which adhered tightly to it. The

space between this pallial line and the outer edge of the valve was

occupied in life by the free portion of the mantle. Frequently a

depression in the pallial line toward the center of the valve is

seen in the posterior end. This is called the /pallial sinus/, and

marks the space occupied by the siphons. The pallial sinus is absent,

moderate, or deep, according as the animal possessed no siphons, or

small or large ones.

The length of bivalve shells is measured from their anterior to their

posterior ends, while the height indicates the greatest diameter

between the umbones and the ventral margin.

The greatest possible degree of variation exists in the structure of

the pelecypod shell. Every degree of thickness from the most fragile,

tissue-like structure to the very heavy and ponderous tests of some

of the /Veneridæ/ is to be found. There is also a range in size

from the very minute /Spheria/ to the giant /Tridacna/ of Eastern

seas, which weighs several hundred pounds. As in the /Gasteropoda/,

there is fortunately a very close parallelism between shell and

anatomical variations. One very quickly learns to place a bivalve in

its systematic position by a mere glance at the shell alone. While

the higher classification into orders, suborders, etc., is based upon

anatomical features, the genera often and the species always are

founded upon conchological or shell characters.

The /Pelecypoda/ offer one of the most interesting fields for

investigation and study among the invertebrates. Although by no means

neglected, they have not received as much attention on the part of

biologists as has been given to other phyla, or indeed to the other

classes of this same phylum.

CLASSIFICATION OF THE PELECYPODA

Nearly every systematic writer upon the mollusks has attempted to

give a good classification of the bivalves, yet none of the results

is wholly satisfactory. The scheme now generally adopted is one based

upon modifications of the gills, or branchiæ, and has practically

replaced all the older classifications, which depended [pg420] upon

the presence or absence of siphons, the degree of mantle fusion,

the arrangement of teeth upon the hinge, the number of adductor

muscles, etc. The idea of arrangement according to gill-structure is

substantially this: the development of the gill from the simplest

and most rudimentary type through successive stages to a higher,

more complex, and presumably more efficient type, marks the natural

progress or development of the pelecypod animal itself. By adopting

the gill as a guide one follows, therefore, a natural method. Upon

the other hand, the presence or absence of siphons, the shape

of the foot, the number of adductor muscles, all depend merely

upon the acquired habits of the animal, these particular features

being subject to modification according to environment and changed

conditions.

The five orders of the /Pelecypoda/ are: /Protobranchiata/,

/Filibranchiata/, /Pseudolamellibranchiata/, /Eulamellibranchiata/,

/Septibranchiata/.

[Illustration: Structure of the branchiæ or gills of pelecypods,

seen diagrammatically in section: A, /Protobranchiata/; B,

/Filibranchiata/; C, /Eulamellibranchiata/; D, /Septibranchiata/;

/e/, /e/, external row of filaments; /i/, /i/, internal row of

filaments; /e´/, external row or plate folded back; /i´/, internal

row folded back; /f/, foot; /m/, mantle; /s/, septum; /v/, visceral

mass.]

The first includes the simpler type of gill as represented in the

accompanying figure (A). Its filaments are short and not reflected.

The second, represented in Fig. B, has the filaments long, reflected,

and connected (each filament to its adjacent ones) by means of

surface cilia. The third type of gill resembles the last except that

the ends of the filaments of the outer gill are attached to the

mantle, and the ends of the filaments of the inner gill are attached

to the foot or visceral mass. The fourth type of gill is far more

highly [pg421] developed. The adjacent filaments are connected, not

by cilia, but by vascular channels, and the depending and recurved

portions of each filament are also connected in a manner presumed to

admit of the passage of blood. This gives to the organ the appearance

of basketwork or network. The ends of the filaments are attached to

the mantle and to the visceral mass, as in the last order, forming

cavities or chambers above (see Fig. C). This order includes the

great majority of the /Pelecypoda/.

The fifth and last order is confined to but two rather obscure

families, in which the gill-development is carried to the point of

substitution of muscular partitions which form a separate chamber

connected with the mantle cavity by a narrow slit, the surface of the

chamber having respiratory functions (Fig. D).

The collector of living marine objects who has become fascinated by

their beauty and who derives pleasure from examining the greater

beauty of their structures will find a rich field for research in

the pelecypod gills. But unless he has time at his disposal and some

skill with a microscope, he would do well not to venture too far into

this alluring but difficult and vexatious subject.

Our coastal waters are fairly rich in bivalves, but the most

strikingly handsome species of this class--and there are many of

them--are inhabitants of warmer seas. Of the great number of bivalves

to be found upon our own shores we can only mention briefly some of

the commonest species.

ORDER =PROTOBRANCHIATA=

FAMILY ~NUCULIDÆ~

In this family the gills are of the simplest and most primitive type.

The mantle-edges are entirely open along the ventral margin, but they

are united posteriorly in some of the /Nuculidæ/ to form two short

siphons. The palps are exceedingly large. The foot is also large,

and by its disk-like surface is adapted to creeping, much as is a

gasteropod foot; its edges are often crenulated or scalloped, and

there is no trace of a byssus. The shells are [pg422] equivalve, and

their most prominent feature is the hinge, which is beset with sharp,

comb-like teeth in two straight rows, one upon each side of a central

pit, a space reserved for the ligament.

GENUS ^Nucula^

^N. proxima.^ The commonest of several species of the genus found

along the New England coast. It is oblique, with a light-olive

epidermis, nacreous interior, and finely crenulated margins. Its

length is about one quarter of an inch. The animal has no siphons.

It lives in either muddy or pebbly stations near the shore, and

probably exists in countless thousands in all the bays and harbors

of the New England coast.

[Illustration: /Nucula proxima./]

GENUS ^Leda^

^L. tenuisulcata.^ This species has a longer shell than the

preceding; it is more produced behind, and is narrowed into a

blunt, slightly gaping point. The epidermis is light greenish, and

the shell has a pearly luster within. The outer surface of the

shell is concentrically grooved; the beaks are smooth. The foot is

disk-shaped, and the animal is provided with small siphons. The

length of this shell is about one inch. Its station is the muddy

bottom in shoal water on the New England coast.

[Illustration: /Leda tenuisulcata./]

GENUS ^Yoldia^

^Y. limatula.^ This species has the same sort of toothed hinge

exhibited in the two preceding species, but the shell is

considerably larger (two inches), with a smooth greenish glazed

epidermis. The beaks are nearly central. The interior of the shell

is light bluish and pearly. The animal has two slender, short,

united siphons and a disk-shaped foot with simple margins. This

species can make excellent use of its foot, for it crawls with

rapidity, and also can execute leaps in an astonishing manner.

Found in muddy stations in shoal water on the New England coast.

[Illustration: /Yoldia limatula./]

^Y. thraciæformis.^ A much larger species, found on the New England

coast. It may be distinguished by a rib-like wave extending

obliquely from the umbones to the ventral margin of the shell. It

measures over [pg423] two and a half inches in length and one and

a half inches in height, and is dark olive-green. The foot is like

that of /Y. limatula/. The labial palps are exceedingly large.

^Y. sapotilla.^ The shell is ovate, prolonged on one side, thin,

fragile, translucent, and covered with a thin, glossy epidermis,

greenish in color. The anterior half is semi-oval, the posterior

portion narrowed and compressed; within it is pearly-white, with a

triangular cartilage cavity, and sixteen to eighteen pointed teeth

on each side. In length it is little less than an inch. Found from

Long Island Sound northward.

[Illustration: /Yoldia thraciæformis./]

[Illustration: /Yoldia sapotilla./]

FAMILY ~SOLENOMYIDÆ~

GENUS ^Solenomya^

Two species of this genus, which are greatly prized by collectors

on account of the extraordinary development of the epidermis of the

shell, occur in New England waters. The strong corneous periostracum

of a deep chestnut-color projects considerably beyond the margins

of the valves; the shells are exceedingly thin and fragile, and are

marked with radiating lines. The two species are easily distinguished

by their difference in size. ^S. velum^ is about one inch long and

one half of an inch high. ^S. borealis^, of arctic range, is quite

twice that size. Their anatomy is similar in essentials to that of

/Yoldia/. These species live near shore in sandy bottoms, and are

occasionally found upon the beach between tides. Chelsea Beach, just

north of Boston, is an often-quoted locality.

[Illustration: /Solenomya velum./]

ORDER =FILIBRANCHIATA=

There are several families of this order which are well represented

in both the Atlantic and the Pacific waters of the United States. The

characteristic feature of this group of bivalves is the filamentous

gill, that is, a gill with the filaments long, doubled back, and

united to each other only by ciliary junctures. These [pg424]

junctures are so slight that they break readily when a specimen of a

gill is handled, leaving the filaments free. The presence of a byssal

gland in the foot, and often a well-developed byssus, is another

characteristic of this order.

FAMILY ~ANOMIIDÆ~

GENUS ^Anomia^

This is a family of peculiar and highly specialized forms. /Anomia/

has an irregularly rounded shell, with one convex and one flat

or concave valve. There is no regular hinge or well-defined

hinge-margin, but a raised fossette, or cartilage plate, occupies a

position at the top of the valves. In the flat valve there is a large

oblong hole just under the apex, through which projects a calcified

byssus, by means of which the animal secures itself to oysters, dead

shells, stones, or any solid object. The anomias, which have become

stationary in habit, have practically lost their foot. The gills are

very large and curved, while all the organs seem to be abnormally

placed on account of the huge byssus and byssal muscle. For the

byssus to pass, as it does, through a specially prepared hole in one

of the valves is an extraordinary departure from the conventional

types of byssiferous species. The heart is not traversed by the

intestine. Altogether, then, /Anomia/ is a very curious genus.

[Illustration: /Anomia simplex/, side view. /Anomia simplex/, from

below.]

^A. simplex.^ The commoner large form of New England. It varies

from one to three inches in diameter, is exceedingly irregular

in shape, and its surface is variously undulated and plaited in

accordance with the surface of the object to which it is attached.

Thousands of these valves, disjointed and separated, are cast upon

the beaches all along our Atlantic coast. They are light green to

salmon- or copper-color, generally fragile and scaly, and have a

peculiarly dulled (as though greased) nacre. [pg425]

^A. aculeata^ is much smaller than the last species, and the

surface of the convex valve is roughened by prickly scales. The

smaller valve is very thin, with an almost circular aperture for

the byssus. Its diameter is about half an inch. Found attached to

stones, etc., about the holdfasts of /Fucus/.

[Illustration: /Anomia aculeata/, from above. /Anomia aculeata/,

from below.]

^A. lampe^, a California species ranging more to the south, is

small (half an inch), and greatly resembles the east-coast /A.

aculeata/, save as regards the smooth surface of the former.

GENUS ^Placunanomia^

^P. macrochisma.^ This species occurs on the Californian coast. It

has the same sort of calcified byssus as /Anomia/, and also the

hole to accommodate it in the smaller valve. The scar formed by the

muscle which controls the byssus is curiously rayed in this genus.

The normal shape of the shell is circular; it is pearly within, and

of a greenish tinge without. Two to four inches in diameter. (Plate

LXXVIII.)

FAMILY ~ARCIDÆ~

GENUS ^Arca^

The /Arcidæ/ may always be distinguished by the long row of comb-like

teeth upon the hinge, the total want of siphons (a fact which may be

discovered in the shell alone by its lack of a pallial sinus), and

the solid trapezoidal or round shell, with its tendency to strong

ribs radiating from the umbones. The periostracum, or epidermis, is

heavy and often velvety or even hairy. The animal of /Arca/ has the

gills placed in an oblique position; the foot is large and strongly

developed. No trace of mantle fusion exists. The mantle-edges bear a

row of composite eyes. The gill-filaments are entirely free, there

being even no ciliary junctions.

[Illustration: /Arca pexata./]

^A. pexata.^ An exceedingly common species in Long Island Sound and

on the coast of New Jersey. The shell is oblong, with prominent

beaks directed forward. The hinge-teeth are arranged in a row

posterior to the beaks, while just under the beaks are a number of

irregular cartilage-pits. About thirty-two to thirty-six radiating

ribs ornament the shell. The inner margins of the shell are rather

deeply scalloped; the epidermis is thick, shaggy, and dark

[pg426] brown. Length two to two and a quarter inches; height two

inches. /A. pexata/ is one of the few pelecypods which have red

blood, a fact which accounts for its popular name of "bloody clam."

^A. ponderosa.^ The most prominent /Arca/ upon our Atlantic

coast, especially south of Virginia. The beaks of this shell are

very prominent, and do not approach each other very closely on

account of the wide dorsal margin of the shells, the large space

between the beaks being occupied by an external ligament. The

hinge-teeth are smaller in the middle. There are from twenty-five

to twenty-eight ribs; the ventral margin of the valves is somewhat

contracted in the middle. Length two and a half inches; height two

inches. Very heavy and solid. This exceedingly common species is

often cast upon the beaches south of Hatteras in numbers beyond

computation. In life it is covered with a heavy, coarse, velvety

epidermis, almost jet-black in color. (Plate LXXVIII.)

^A. noæ.^ The well-known "Noah's-ark" shell, a common species

along the shores of the Southeastern States. It also occurs in

the Mediterranean. Unlike most arcas, it spins a byssus, by means

of which it attaches itself to the under surfaces of stones at

low water. The hinge-margin is perfectly straight and regularly

toothed. The beaks are high and are situated very far forward. The

dorsal margin of the valves is strikingly large, and is marked by

lattice-like grooves; it forms a concave surface over an inch in

width between the umbones. The shell is strongly ribbed without.

The ventral margin of the valves is sinuous and gapes slightly at a

central point for the accommodation of the byssus. (Plate LXXVIII.)

FAMILY ~MYTILIDÆ~

GENERA ^Mytilus^, ^Modiola^

[Illustration: PLATE LXXVIII. Placunanomia macrochisma. Arca

ponderosa. Arca noæ. Mytilus hamatus.]

The /Mytilidæ/ are a large family, including the mussels, so

commonly found between tides upon all shores. The two ordinary

genera /Mytilus/ and /Modiola/, which often occur associated

together upon our eastern coast, may readily be distinguished one

from the other by the position of their beaks. In the former genus

the beak is terminal, that is, it is situated at the very tip-end

of the shell; in the latter genus it is not quite terminal. Aside

from this simple feature, the genera are practically the same, the

animals being identical. /Mytilus/ and /Modiola/, commonly known as

mussels, have acquired the stationary habit and are provided with a

relatively small foot (in some species amounting to no more than a

mere tubercle); but in place of a useful foot is a well-developed

byssogenous gland, which secretes an [pg427] exceedingly tough,

fibrous byssus. By means of this the animal may not only attach

itself firmly to any sort of object, but may actually move about.

Fibers of the byssus are thrown out, and, as though possessed of

life, they seize upon objects in the direction in which /Mytilus/

desires to move, and by contraction of the muscles which control

the byssus the animal is drawn forward, the operation being then

repeated. It must be a very tedious method of travel. However, the

/Mytilidæ/ are not restless creatures. They pass their lives content

to remain firmly fixed to some object, and their movements, if any,

are within a very narrow circle. The animal has very long gills

of the usual filamentous type. The mantle fuses at one point to

form an anal siphon, the lower or branchial one being, therefore,

functional. The palps are large. One curious feature of this group is

the enormous extent of the genital glands, which actually appear to

pervade the entire structure of the animal, gills, mantle, foot, and

all. At times the whole being is a veritable receptacle for myriads

of tiny yellowish eggs.

[Illustration: /Mytilus edulis/, typical form.]

The /Mytilidæ/ are of universal distribution, and are for the most

part of littoral or shallow-water range. Some species are esteemed as

an article of food, notably /Mytilus edulis/.

Mussel-culture has been profitably carried on in France for a long

time, but the genus has not been utilized to any extent as food in

this country. [pg428]

^Mytilus edulis^ is exceedingly abundant along the New England

coast. It lives in colonies, often between tides, in pebbly

stations among large rocks. It is always so fastened by its byssus

that the beaks of the valves point downward, and the ventral margin

projects above the sand or mud. The color of the epidermis in the

adult form is black or a deep blue-black; the shell proper is

violet. Hinge-teeth are wanting. Length two and a half inches. A

variety of this species, ^M. pellucidus^, is often found associated

with the typical form. It is brightly rayed in green and yellow.

/M. edulis/ occurs in Europe, where it is quite extensively used as

food. It also occurs (by importation) in San Francisco Bay.

[Illustration: /Mytilus edulis/, rayed-color variety.]

^M. hamatus^ has a more southern range than has /M. edulis/, and

is found from the Chesapeake southward. Its shell is considerably

twisted just below the umbonal region, while its whole surface is

densely striated. Its color is dark fuscous. Length one to two

inches. It is found in great numbers attached to oysters by its

byssus. In Florida it is very common. (Plate LXXVIII.)

^M. californicus.^ A common west-coast species, which finds its

station among rocks exposed to the surf. It is about the same size

as /M. edulis/, but has a lighter brownish glossy epidermis and

several conspicuous, well-rounded, radiating ribs. The animal is

orange-colored.

[Illustration: /Modiola modiolus./]

^Modiola modiolus.^ After violent storms upon the New England

coast, when a large /Laminaria/ is wrenched from its rocky bed

and washed ashore, its roots will, in many cases, be found

clinging to this large mussel. The thick glossy epidermis of deep

chestnut-color folds over the margin of the valves, and the outer

surface, especially near the ventral margin, is covered with a

tough hairy growth. Length four to five inches. The animal is

orange-red. The great size and swelling fullness of this species

at once distinguish it from all others upon our coast. It is not a

shallow-water form, but is extremely common upon all beaches north

of Hatteras. It also occurs in Alaskan waters to Puget Sound, where

it is known as the "great horse-mussel." Sometimes these large

modiolas may be found in rocky tide-pools which are washed by the

surf at high tide. They hide far back in the crevices of boulders,

and [pg429] are not easily detected. They are not uncommon in

such stations at Mount Desert, Maine.

[Illustration: /Modiola plicatula/, typical form.]

^M. plicatula.^ This species of /Modiola/ ranges from Canada to

Hatteras, and inhabits the tidal waters of streams, sheltered

muddy reaches among reeds, and tidal flats. It is a dingy-looking

shell, ornamented with numerous radiating ribs, which are very

fine upon the anterior portion of the shell. The epidermis is thin

and of a dirty yellowish-green color. Within it is silvery-white.

In the ventral margin there is an opening for the accommodation

of a byssus. Length about three inches in New England; slightly

larger at Norfolk. There is probably no muddy reach of land that

is exposed at low tide from Maine to the Carolinas that is not

inhabited by /M. plicatula/.

^M. tulipa.^ This is the "show shell" of the genus /Modiola/ in

American waters. It belongs to the Southern fauna, and, like the

others of its genus, it moors itself to wood or other solid objects

by means of its byssus. It is of about the same size as the last

species, but is perfectly smooth and of a bright-yellowish color,

with dark rays over the central portion.

[Illustration: /Modiola nigra./]

^M. recta.^ A species of /Modiola/ fairly abundant on the Pacific

coast from Vancouver to southern California. It has a long, narrow

shell with a dark-brown glossy epidermis; lighter posteriorly, and

with a short hairy growth. The interior is white. Length three to

four inches.

ORDER =PSEUDOLAMELLIBRANCHIATA=

This third order of /Pelecypoda/ is made up of a number of families

in which the gills are filamentous, but in which the filaments

[pg430] have become united at their ends to the mantle (on the outer

gills) and to the body-mass (on the inner gills). Here also the first

traces of the higher type of gill found in the next order appear;

that is, a gill in which the filaments are connected by vascular

channels instead of by cilia. This order therefore is presumed to

connect the true filamentous type of gill with the fully developed

lamellar type. As the filaments do not always fuse with the mantle

or foot, the description of the pseudolamellibranch gill becomes

somewhat vague, and there is some room for doubt whether this order

should exist at all.

Most of the genera placed in it are monomyarian; that is, they have

but one adductor muscle, or if two, the anterior one is very small

and unimportant. The mantle-edges are entirely open, there being no

regularly formed siphons. As a rule, the foot is exceedingly small or

quite aborted.

FAMILY ~AVICULIDÆ~

In this family there is an exception to the rule just stated: the

foot is long. There is a byssus, and the gills (by their outer

ascending filaments) are concrescent with the mantle.

The interior of all the /Aviculidæ/ is of a highly polished nacre,

and some of the larger species have been extensively collected

for mother-of-pearl. To the /Aviculidæ/ belong the pearl-oysters

(/Meleagrina margaritifera/).

A delightful air of romance and adventure surrounds the

pearl-fisheries, about which much has been written. The pearl

is an abnormal product formed by the deposition of nacre around

some foreign object, such as a grain of sand, or--usually, it is

said--an egg which has failed to develop properly. They are seldom

found in individuals having favorable conditions of growth, but

those which are greatly crowded together and covered with various

parasites and growths are most productive of them. The pearl is

the same in substance as the nacreous shell of the pearl-oyster,

and its iridescence is due to the fine striæ of the undulating

layers of which it is composed. The pearl as well as the shell

is produced by the shell-glands of the mantle. The value of the

[pg431] pearl is based on the brilliancy of the nacre, the size,

and the form. Luster, or "orient," is to the pearl what brilliancy

is to the diamond. The round form has the greatest value, next

the pear-shape, and lastly the oval. Pearls of inferior value are

produced by other species than /Meleagrina margaritifera/, the true

pearl-oyster. Many bivalves secrete similar bodies, but as they have

the nature of the shell, those produced by mollusks having lusterless

interiors are of no value. Beautiful pink pearls are found in the

gasteropod /Strombus gigas/, the conch-shell of the West Indies. The

shells of the pearl-oyster are themselves very valuable, being the

"mother-of-pearl" used in the manufacture of buttons, knife-handles,

inlay-work, and so on. They have three grades of commercial value; of

the first are the "silver-lipped," from the South Seas, of the second

the "black-lipped," from Manila and Ceylon, and of the third the

"bullock-shells," from Panama.

GENUS ^Avicula^

^A. atlantica.^ A Floridian species which is often found attached

by its byssus to large algæ which have been washed upon the beach.

The shell is reddish-brown, with many white radial lines. Its

obliquely oval shape, the long wing-like extension of the dorsal

margin, the inequivalve shells, and the byssal sinus placed just

below the forward extension of the hinge, are characteristics which

will enable one to recognize the species at once. The structure of

the shell is unusual in being so largely composed of organic matter

that it possesses elasticity near its thinner edges.

GENUS ^Pinna^

^P. muricata^ and ^P. seminuda^. Two species of this family which

are very abundant in Floridian waters and are often to be found

associated upon the muddy or sandy shores of bays. Like /Modiola

plicatula/, they attach themselves by means of their byssus to

shells or stones which lie under the surface. With the pointed end

of the shell directed downward, they remain almost wholly concealed

in the sand. Only about one quarter of an inch of the broad end

of the shell projects above the sand. The edges of the valves are

as sharp as knife-blades, and great caution must be used while

walking barefooted along a beach inhabited by /Pinna/. The shells

of both species are of a triangular wedge-shape and are composed

of a translucent crystalline matter. /P. muricata/ is beset with

triangular erect scales which project out like spines. Their edges

are also sharp like pieces of broken glass. /P. seminuda/ also has

these raised scales, but they are far more numerous [pg432] and

much smaller, and are arranged in closely packed radiating rows,

the scales becoming obsolete near the umbones. The mantle of the

animal is doubly fringed, and much decorated upon that portion

which may be protruded from the shell. The posterior adductor is

very large and strong; the anterior one has almost disappeared. The

foot is long and slender, but is evidently a useless appendage,

for the animal's habit is stationary. The byssus is large and very

strong. Gloves have been made from the byssal fibers of /Pinna/

mixed with silk. The gills are very long and are distinctly /not/

filamentous, the adjacent filaments being clearly united by

vascular channels. A very curious development of the osphradium

(see page 339) into an erectile process capable of projection

beyond the margin of the shell is a unique feature of /Pinna/.

Sometimes thousands of pinnas are torn loose by storms and cast

upon the beaches. They do not range north of Hatteras. (Plate

LXXIX.)

GENUS ^Perna^

^P. ephippium.^ A West Indian shell, also quite common on the

east coast of Florida, and especially upon the Keys. It attaches

itself by the byssus in great bunches to mangrove roots, sticks,

and all manner of rubbish in brackish water. It has a very flat,

irregularly shaped shell of a horn-color, and is from two to

three inches across. The distinguishing feature of /Perna/ is the

hinge. It is straight and without teeth, but is marked by a row of

transverse grooves to which the ligament is attached. These grooves

constitute a row of cartilage-pits.

FAMILY ~OSTREIDÆ~

This family probably interests more people than any other one in the

class save /Aviculidæ/. The latter furnishes the pearl-oysters, the

former the edible oysters, the two thus appealing to two very strong

human cravings--those of vanity and hunger.

[Illustration: PLATE LXXIX. Pinna muricata. Pinna seminuda. Pecten

hastatus.]

Few realize what an enormous business the oyster trade has become

in the United States. The value of it is stated to be over thirteen

million dollars annually, twenty-five million bushels of oysters

being taken from the Chesapeake alone. The edibility of the

oyster has been known from early times, for vast heaps of empty

oyster-shells, known as kitchen-middens, occur in various parts of

the world. Some of them are of such size and extent as to warrant

the belief that their formation must have required centuries.

Shell-mounds are found along the coasts of Florida and are of some

archæological value. The cultivation of oysters as recorded by Pliny

dates from the first century B.C., at which [pg433] time a Roman

named Sergius Orata first cultivated oysters at Baiæ. The acuteness

of the gastronomic sense of a Roman epicure is thus described by

Juvenal:

He could tell

At the first mouthful if his oysters fed

On the Rutupian or the Lucrine bed

Or at Circeii.

The poet Gay's opinion is expressed thus:

The man had sure a palate cover'd o'er

With brass or steel, that on the rocky shore

First broke the oozy oyster's pearly coat,

And risk'd the living morsel down his throat.

The methods employed in oyster-farming resemble those of agriculture,

in that the bed is prepared, seed is sown, superfluous and foreign

growths are weeded out, enemies are driven off, and the crop is

harvested at stated seasons. The oyster is ovoviviparous; that is,

it retains its eggs until they are partly matured. These are held in

the gills and mantle folds until the time of spawning, which begins

in May and lasts through the summer months. The larvæ are ejected as

ciliated spheres, called spat, and swim freely about for some time,

often several days, before finding a resting-spot. The oyster-grower

secures many of the larvæ by placing in their way substances to

which they can attach themselves. The American culturist strews his

carefully prepared beds with empty oyster-shells, on which the spat

settle, and the seed is thus secured; for the spat, once fastened,

lose the power of locomotion and become fixed. At the end of a year

the shells which hold the young oysters (now about an inch long

and called "fry") are taken up, and the fry are thinned out and

replanted, or are sold to other oyster-farmers.

During the period of their growth the oysters are sometimes

transplanted several times. At the end of three to five years they

have attained marketable size, and the beds are then harvested and

prepared for another crop. Some oystermen have several acres of

bottom under cultivation. These areas are obtained by purchase or

grant from the State, and their limits are as defined [pg434] as

are the fenced-off acres of upland meadows. The business of the

oyster-culturist is to plant the young oysters and watch their

development, keeping the beds thinned, that the oysters may not be

too crowded for their normal and symmetrical growth, and protecting

them from their enemies, of which there are many. The principal

enemies of the oyster are the starfish and the predaceous mollusks

/Urosalpinx/ and /Nassa/. Whole beds have been known to be destroyed

in a single night by the visitations of starfishes, hence a constant

watchfulness is required on the part of the oysterman. Policing the

oyster-farms is another of his cares, for pirates abound, and a bed

may be robbed in the night as easily as an orchard may be despoiled

of its fruit. Oyster-culture is carried on extensively in Long

Island Sound, on the coasts of New Jersey and Virginia, and in the

Chesapeake Bay. The oysters from certain localities are esteemed more

than others, the flavor of the oyster being very dependent upon the

purity of the water and on the organisms upon which it feeds. It has

been definitely shown that oysters grown in contaminated waters have

been the agents of transmitting disease, notably typhoid fever and

cholera.

Oyster-culture has reached the highest degree of perfection in

France, where miles of muddy shores left by the ebb-tide are utilized

for the purpose. The famous /parc/ at Arcachon, covering ten thousand

acres, illustrates the system generally practised. The spat is there

collected on tiles coated with cement, piled in layers crosswise, and

secured in crates. These tiles are exposed in favorable localities

and collect the swimming embryos. The rough cement holding the

spat is then chipped off the tiles and placed in wire trays. These

/ambulances/, or /caisses ostreophiles/, placed between short posts,

protect the fry from their enemies. At low tide the young oysters

are carefully examined and sorted, and at the right age they are

removed to open areas. The parc is divided into regular squares by

canals of suitable width, some of the squares having banks and gates

to retain the water of the receding tide if desired. Each man's parc

is separated from that of his neighbor by canals of greater width,

and often by stakes having a few branches on the ends. These [pg435]

/pignons/, which sway in the wind, are said to frighten away the

predaceous ray which is apt to hover about the preserves. The parcs

are finally thinned out by sending the oysters to other parcs to be

fattened. There is a celebrated /parc d'élevage/ at Marennes. It is

a collection of artificial ponds, the floors of which are covered

with algæ, which harbor vast numbers of diatoms and other microscopic

organisms on which the oysters feed. The green diatom (/Navicula

ostrearia/) gives to the oysters of Marennes the green color and

peculiar flavor which is so much esteemed by the epicures of France.

To the American, however, the green oyster is not acceptable.

GENUS ^Ostrea^

^O. virginica.^ A description of this species, our common oyster,

is hardly necessary. Every one has seen the rough, shaggy, unlovely

shell. The hinge is toothless, but has a wide depression for the

ligament. The animal, having stationary habits, has practically no

foot at all. There is but one large adductor muscle, around which

curve the gills, the latter being united to each other posteriorly.

The mantle margin is finely and doubly fringed. Although /Ostrea/

is a stationary mollusk, it has no byssus.

/O. virginica/ has been introduced at San Francisco, where it

lives well, but does not seem to multiply very rapidly. The native

species, ^O. lurida^, is about two inches long, dark in color, and

stained a purplish hue. It is not very delicately flavored.

^O. frons.^ This species has a thinner shell than /O. virginica/,

with coarsely serrated margins. It occurs in beds in the

neighborhood of mangroves all along our South Atlantic shores. It

cannot compare with its Northern relative in flavor, but, like the

European ^Ostrea edulis^, it is sometimes "not bad."

FAMILY ~PECTINIDÆ~

GENUS ^Pecten^