THE GRAYLING AND THE SMELT
=THE Grayling, or Thymallidæ.=—The small family of _Thymallidæ_, or
grayling, is composed of finely organized fishes allied to the trout,
but differing in having the frontal bones meeting on the middle line of
the skull, thus excluding the frontals from contact with the
supraoccipital. The anterior half of the very high dorsal is made up of
unbranched simple rays. There is but one genus, _Thymallus_, comprising
very noble game-fishes characteristic of subarctic streams.
[Illustration:
FIG. 80.—Alaska Grayling, _Thymallus signifer_ Richardson. Nulato,
Alaska.
]
The grayling, _Thymallus_, of Europe, is termed by Saint Ambrose "the
flower of fishes." The teeth on the tongue, found in all the trout and
salmon, are obsolete in the grayling. The chief distinctive peculiarity
of the genus _Thymallus_ is the great development of the dorsal fin,
which has more rays (20 to 24) than are found in any of the _Salmonidæ_,
and the fin is also higher. All the species are gaily colored, the
dorsal fin especially being marked with purplish or greenish bands and
bright rose-colored spots; while the body is mostly purplish gray, often
with spots of black. Most of the species rarely exceed a foot in length,
but northward they grow larger. Grayling weighing five pounds have been
taken in England; and according to Dr. Day they are said in Lapland to
reach a weight of eight or nine pounds. The grayling in all countries
frequent clear, cold brooks, and rarely, if ever, enter the sea, or even
the larger lakes. They congregate in small shoals in the streams, and
prefer those which have a succession of pools and shallows, with a sandy
or gravelly rather than rocky bottom. The grayling spawns on the
shallows in April or May (in England). It is non-migratory in its
habits, depositing its ova in the neighborhood of its usual haunts. The
ova are far more delicate and easily killed than those of the trout or
charr. The grayling and the trout often inhabit the same waters, but not
altogether in harmony. It is said that the grayling devours the eggs of
the trout. It is certain that the trout feed on the young grayling. As a
food-fish, the grayling of course ranks high; and it is beloved by the
sportsman. They are considered gamy fishes, although less strong than
the brook-trout, and perhaps less wary. The five or six known species of
grayling are very closely related, and are doubtless comparatively
recent offshoots from a common stock, which has now spread itself widely
through the northern regions.
The common grayling of Europe (_Thymallus thymallus_) is found
throughout northern Europe, and as far south as the mountains of Hungary
and northern Italy. The name _Thymallus_ was given by the ancients,
because the fish, when fresh, was said to have the odor of water-thyme.
Grayling belonging to this or other species are found in the waters of
Russia and Siberia.
The American grayling (_Thymallus signifer_) is widely distributed in
British America and Alaska. In the Yukon it is very abundant, rising
readily to the fly. In several streams in northern Michigan, Au Sable
River, and Jordan River in the southern peninsula, and Otter Creek near
Keweenaw in the northern peninsula, occurs a dwarfish variety or species
with shorter and lower dorsal fins, known to anglers as the Michigan
grayling (_Thymallus tricolor_). This form has a longer head, rather
smaller scales, and the dorsal fin rather lower than in the northern
form (_signifer_); but the constancy of these characters in specimens
from intermediate localities is yet to be proved. Another very similar
form, called _Thymallus montanus_, occurs in the Gallatin, Madison, and
other rivers of Western Montana tributary to the Missouri. It is locally
still abundant and one of the finest of game-fishes. It is probable that
the grayling once had a wider range to the southward than now, and that
so far as the waters of the United States are concerned it is tending
toward extinction. This tendency is, of course, being accelerated in
Michigan by lumbermen and anglers. The colonies of grayling in Michigan
and Montana are probably remains of a post-glacial fauna.
[Illustration:
FIG. 81.—Michigan Grayling, _Thymallus tricolor_ Cope. Au Sable River,
Mich.
]
=The Argentinidæ.=—The family of _Argentinidæ_, or smelt, is very
closely related to the _Salmonidæ_, representing a dwarf series of
similar type. The chief essential difference lies in the form of the
stomach, which is a blind sac, the two openings near together, and about
the second or pyloric opening there are few if any pyloric cæca. In all
the _Salmonidæ_ the stomach has the form of a siphon, and about the
pylorus there are very many pyloric cæca. The smelt have the adipose fin
and the general structure of the salmon. All the species are small in
size, and most of them are strictly marine, though some of them ascend
the rivers to spawn, just as salmon do, but not going very far. A few
kinds become landlocked in ponds. Most of the species are confined to
the north temperate zone, and a few sink into the deep seas. All that
are sufficiently abundant furnish excellent food, the flesh being
extremely delicate and often charged with a fragrant oil easy of
digestion.
[Illustration:
FIG. 82.—Smelt, _Osmerus mordux_ (Mitchill). Wood's Hole, Mass.
]
The best-known genus, _Osmerus_, includes the smelt, or spirling
(éperlan), of Europe, and its relatives, all excellent food-fishes,
although quickly spoiling in warm weather. _Osmerus eperlanus_ is the
European species; _Osmerus mordax_ of our eastern coast is very much
like it, as is also the rainbow-smelt, _Osmerus dentex_ of Japan and
Alaska. A larger smelt, _Osmerus albatrossis_, occurs on the coast of
Alaska, and a small and feeble one, _Osmerus thaleichthys_, mixed with
other small or delicate fishes, is the whitebait of the San Francisco
restaurants. The whitebait of the London epicure is made up of the young
of herrings and sprats of different species. The still more delicate
whitebait of the Hong Kong hotels is the icefish, _Salanx chinensis_.
_Retropinna retropinna_, so called from the backward insertion of its
dorsal, is the excellent smelt of the rivers of New Zealand. All the
other species belong to northern waters. _Mesopus_, the surf-smelt, has
a smaller mouth than _Osmerus_ and inhabits the North Pacific. The
California species, _Mesopus pretiosus_, of Neah Bay has, according to
James G. Swan, "the belly covered with a coating of yellow fat which
imparts an oily appearance to the water where the fish has been cleansed
or washed and makes them the very perfection of pan-fish." This species
spawns in late summer along the surf-line. According to Mr. Swan the
water seems to be filled with them. "They come in with the flood-tide,
and when a wave breaks upon the beach they crowd up into the very foam,
and as the surf recedes many will be seen flapping on the sand and
shingle, but invariably returning with the undertow to deeper water."
The Quilliute Indians of Washington believe that "the first surf-smelts
that appear must not be sold or given away to be taken to another place,
nor must they be cut transversely, but split open with a mussel-shell."
The surf-smelt is marine, as is also a similar species, _Mesopus
japonicus_, in Japan. _Mesopus olidus_, the pond-smelt of Alaska,
Kamchatka, and Northern Japan, spawns in fresh-water ponds.
[Illustration:
FIG. 83.—Eulachon, or Ulchen. _Thaleichthys pretiosus_ Girard.
Columbia River. Family _Argentinidæ_.
]
Still more excellent as a food-fish than even these exquisite species is
the famous eulachon, or candle-fish (_Thaleichthys pacificus_). The
Chinook name, usually written eulachon, is perhaps more accurately
represented as ulchen. This little fish has the form of a smelt and
reaches the length of nearly a foot. In the spring it ascends in
enormous numbers all the rivers north of the Columbia, as far as
Skaguay, for a short distance for the purpose of spawning. These runs
take place usually in advance of the salmon-runs. Various predatory
fishes and sea-birds persecute the eulachon during its runs, and even
the stomachs of the sturgeons are often found full of the little fishes,
which they have taken in by their sucker-like mouths. At the time of the
runs the eulachon are extremely fat, so much so that it is said that
when dried and a wick drawn through the body they may be used as
candles. On Nass River, in British Columbia, a stream in which their run
is greatest, there is a factory for the manufacture of eulachon-oil from
them. This delicate oil is proposed as a substitute for cod-liver oil in
medicine. Whatever may be its merits in this regard, it has the
disadvantage in respect to salability of being semi-solid or lard-like
at ordinary temperatures, requiring melting to make it flow as oil. The
eulachon is a favorite pan-fish in British Columbia. The writer has had
considerable experience with it, broiled and fried, in its native
region, and has no hesitation in declaring it to be the best-flavored
food-fish in American waters. It is fat, tender, juicy, and richly
flavored, with comparatively few troublesome bones. It does not,
however, bear transportation well. The Indians in Alaska bury the
eulachon in the ground in great masses. After the fish are well decayed
they are taken out and the oil pressed from them. The odor of the fish
and the oil is then very offensive, less so, however, than that of some
forms of cheese eaten by civilized people.
[Illustration:
FIG. 84.—Page of William Clark's handwriting with sketch of the
Eulachon (_Thaleichthys pacificus_), the first notice of the
species. Columbia River, 1805. (Expedition of Lewis & Clark.)
(Reproduced from the original in the possession of his granddaughter
Mrs. Julia Clark Voorhis, through the courtesy of Messrs. Dodd, Mead
& Company, publishers of the "Original Journals of the Lewis and
Clark Expedition.")
]
The capelin (_Mallotus villosus_) closely resembles the eulachon,
differing mainly in its broader pectorals and in the peculiar scales of
the males. In the male fish a band of scales above the lateral line and
along each side of the belly become elongate, closely imbricated, with
the free points projecting, giving the body a villous appearance. It is
very abundant on the coasts of Arctic America, both in the Atlantic and
the Pacific, and is an important source of food for the natives of those
regions.
[Illustration:
FIG. 85.—Capelin, _Mallotus villosus_ L. Crosswater Bay.
]
This species spawns in the surf, and the writer has seen them in August
cast on the shores of the Alaskan islands (as at Metlakahtla in 1897),
living and dead, in numbers which seem incredible. The males are then
distorted, and it seems likely that all of them perish after spawning.
The young are abundant in all the northern fiords. Even more inordinate
numbers are reported from the shores of Greenland.
The capelin seems to be inferior to the eulachon as a food-fish, but to
the natives of arctic regions in both hemispheres it is a very important
article of food. Fossil capelin are found in abundance in recent shales
in Greenland enveloped in nodules of clay. In the open waters about the
Aleutian Islands a small smelt, _Therobromus callorhini_, occurs in very
great abundance and forms the chief part of the summer food of the
fur-seal. Strangely enough, no complete specimen of this fish has yet
been seen by man, although thousands of fragments have been taken from
seals' stomachs. From these fragments Mr. Frederick A. Lucas has
reconstructed the fish, which must be an ally of the surf-smelt,
probably spawning in the open ocean of the north.
The silvery species called _Argentina_ live in deeper water and have no
commercial importance. _Argentina silus_, with prickly scales, occurs in
the North Sea. Several fossils have been doubtfully referred to
_Osmerus_.
=The Microstomidæ.=—The small family of _Microstomidæ_ consists of a few
degraded smelt, slender in form, with feeble mouth and but three or four
branchiostegals, rarely taken in the deep seas. _Nansenia grœnlandica_
was found by Reinhardt off the coast of Greenland, and six or eight
other species of _Microstoma_ and _Bathylagus_ have been brought in by
the deep-sea explorations.
=The Salangidæ, or Icefishes.=—Still more feeble and insignificant are
the species of _Salangidæ_, icefishes, or Chinese whitebait, which may
be described as _Salmonidæ_ reduced to the lowest terms. The body is
long and slender, perfectly translucent, almost naked, and with the
skeleton scarcely ossified. The fins are like those of the salmon, the
head is depressed, the jaws long and broad, somewhat like the bill of a
duck, and within there are a few disproportionately strong canine teeth,
those of the lower jaw somewhat piercing the upper. The alimentary canal
is straight for its whole length, without pyloric cæca. These little
fishes, two to five inches long, live in the sea in enormous numbers and
ascend the rivers of eastern Asia for the purpose of spawning. It is
thought by some that they are annual fishes, all dying in the fall after
reproduction, the species living through the winter only within its
eggs. But this is only suspected, not proved, and the species will repay
the careful study which some of the excellent naturalists of Japan are
sure before long to give to it. The species of _Salanx_ are known as
whitebait, in Japan as _Shiro-uwo_, which means exactly the same thing.
They are also sometimes called icefish (_Hingio_), which, being used for
no other fish, may be adopted as a group name for _Salanx_.
The species are _Salanx chinensis_ from Canton, _Salanx hyalo cranius_
from Korea and northern China, _Salanx microdon_ from northern Japan,
and _Salanx ariakensis_ from the southern island of Kiusiu. The Japanese
fishes are species still smaller and feebler than their relatives from
the mainland.
=The Haplochitonidæ.=—The _Haplochitonidæ_ are trout-like fishes of the
south temperate zone, differing from the _Salmonidæ_ mainly in the
extension of the premaxillary until, as in the perch-like fishes, it
forms the outer border of the upper jaw. The adipose fin is present as
in all the salmon and smelt. _Haplochiton_ of Tierra del Fuego and the
Falkland Islands is naked, while in _Prototroctes_ of Australia and New
Zealand the body, as in all salmon, trout, and smelt, is covered with
scales. _Prototroctes maræna_ is the yarra herring of Australia. The
closely related family of _Galaxiidæ_, also Australian, but lacking the
adipose fin, is mentioned in a later chapter.
[Illustration:
FIG. 86.—Icefish, _Salanx hyalocranius_ Abbott. Family _Salangidæ_.
Tientsin, China.
]
=Stomiatidæ.=—The _Stomiatidæ_, with elongate bodies, have the mouth
enormous, with fang-like teeth, usually barbed. Of the several species
_Stomias ferox_ is best known. According to Dr. Boulenger, these fishes
are true _Isospondyli_.
[Illustration:
FIG. 87.—_Stomias ferox_ Reinhardt. Banquereau.
]
_Astronesthidæ_ is another small group of small fishes naked and black,
with long canines, found in the deep sea.
The _Malacosteidæ_ is a related group with extremely distensible mouth,
the species capable of swallowing fishes much larger than themselves.
The viper-fishes (_Chauliodontidæ_) are very feeble and very voracious
little fishes occasionally brought up from the depths. _Chauliodus
sloanei_ is notable for the length of the fangs.
Much smaller and feebler are the species of the closely related family
of _Gonostomidæ_. _Gonostoma_ and _Cyclothone_ dwell in oceanic abysses.
One species, _Cyclothone elongata_, occurs at the depth of from half a
mile to nearly four miles almost everywhere throughout the oceans. It is
probably the most widely distributed, as well as one of the feeblest and
most fragile, of all bassalian or deep-sea fishes.
[Illustration:
FIG. 88.—_Chauliodus sloanei_ Schneider. Grand Banks.
]
=Suborder Iniomi, the Lantern-fishes.=—The suborder _Iniomi_ (ἰνίον,
nape; ὤμος, shoulder) comprises soft-rayed fishes, in which the
shoulder-girdle has more or less lost its completeness of structure as
part of the degradation consequent on life in the abysses of the sea.
These features distinguish these forms from the true _Isospondyli_, but
only in a very few of the species have these characters been verified by
actual examination of the skeleton. The mesocoracoid arch is wanting or
atrophied in all of the species examined, and the orbitosphenoid is
lacking, so far as known. The group thus agrees in most technical
characters with the _Haplomi_, in which group they are placed by Dr.
Boulenger. On the other hand the relationships to the _Isospondyli_ are
very close, and the _Iniomi_ have many traits suggesting degenerate
_Isospondyli_. The post-temporal has lost its usual hold on the skull
and may touch the occiput on the sides of the cranium. Nearly all the
species are soft in body, black or silvery over black in color, and all
that live in the deep sea are provided with luminous spots or glands
giving light in the abysmal depths. These spots are wanting in the few
shore species, as also in those which approach most nearly to the
_Salmonidæ_, these being presumably the most primitive of the group. In
these also the post-temporal touches the back of the cranium near the
side. In the majority of the _Iniomi_ the adipose fin of the _Salmonidæ_
is retained. From the phosphorescent spots is derived the general name
of lantern-fishes applied of late years to many of the species. Most of
these are of recent discovery, results of the remarkable work in
deep-sea dredging begun by the _Albatross_ and the _Challenger_. All of
the species are carnivorous, and some, in spite of their feeble muscles,
are exceedingly voracious, the mouth being armed with veritable daggers
and spears.
=Aulopidæ.=—Most primitive of the _Iniomi_ is the family of _Aulopidæ_,
having an adipose fin, a normal maxillary, and no luminous spots. The
rough firm scales suggest those of the berycoid fishes. The few species
of _Aulopus_ and _Chlorophthalmus_ are found in moderate depths.
_Aulopus purpurissatus_ is the "Sergeant Baker" of the Australian
fishermen.
[Illustration:
FIG. 89.—Lizard-fish, _Synodus fætens_ L. Charleston, S. C.
]
=The Lizard-fishes.=—The _Synodontidæ_, or lizard-fishes, have
lizard-like heads with very large mouth. The head is scaly, a character
rare among the soft-rayed fishes. The slender maxillary is grown fast to
the premaxillary, and the color is not black. Most of the species are
shore-fishes and some are brightly colored. _Synodus fætens_ is the
common lizard-fish, or galliwasp, of our Atlantic coast. _Synodus
varius_ of the Pacific is brightly colored, olive-green and orange-red
types of coloration existing at different depths. Most of the species
lie close to the bottom and are mottled gray like coral sand. A few
occur in oceanic depths. The "Bombay duck" of the fishermen of India is
a species of _Harpodon_, _H. nehereus_, with large mouth and
arrow-shaped teeth. The dried fish is used as a relish.
The _Benthosauridæ_ are deep-sea fishes of similar type, but with
distinct maxillaries. The _Bathypteroidæ_, of the deep seas, resemble
_Aulopus_, but have the upper and lower pectoral rays filiform,
developed as organs of touch in the depths in which the small eyes
become practically useless.
=Ipnopidæ.=—In the _Ipnopidæ_ the head is depressed above and the two
eyes are flattened and widened so as to occupy most of its upper
surface. These structures were at first supposed to be luminous organs,
but Professor Moseley has shown them to be eyes. "They show a flattened
cornea extending along the median line of the snout, with a large retina
composed of peculiar rods which form a complicated apparatus destined
undoubtedly to produce an image and to receive especial luminous rays."
The single species, _Ipnops murrayi_, is black in color and found at the
depth of 2½ miles in various seas.
[Illustration:
FIG. 90.—_Ipnops murrayi_ Günther.
]
The existence of well-developed eyes among fishes destined to live in
the dark abysses of the ocean seems at first contradictory, but we must
remember that these singular forms are descendants of immigrants from
the shore and from the surface. "In some cases the eyes have not been
specially modified, but in others there have been modifications of a
luminous mucous membrane leading on the one hand to phosphorescent
organs more or less specialized, or on the other to such remarkable
structures as the eyes of _Ipnops_, intermediate between true eyes and
phosphorescent plates. In fishes which cannot see, and which retain for
their guidance only the general sensibility of the integuments and the
lateral line, these parts soon acquire a very great delicacy. The same
is the case with tactile organs (as in _Bathypterois_ and
_Benthosaurus_), and experiments show that barbels may become organs of
touch adapted to aquatic life, sensitive to the faintest movements or
the slightest displacement, with power to give the blinded fishes full
cognizance of the medium in which they live."
=Rondeletiidæ.=—The _Rondeletiidæ_ are naked black fishes with small
eyes, without adipose fin and without luminous spots, taken at great
depths in the Atlantic. The relationship of these fishes is wholly
uncertain.
[Illustration:
FIG. 91.—_Cetomimus gillii_ Goode & Bean. Gulf Stream.
]
The _Cetomimidæ_ are near allies of the _Rondeletiidæ_, having the mouth
excessively large, with the peculiar form seen in the right whales,
which these little fishes curiously resemble.
[Illustration:
FIG. 92.—Headlight Fish, _Diaphus lucidus_ Goode & Bean. Gulf Stream.
]
=Myctophidæ.=—The large family of _Myctophidæ_, or lantern-fishes, is
made up of small fishes allied to the _Aulopidæ_, but with the body
covered with luminous dots, highly specialized and symmetrically
arranged. Most of them belong to the deep sea, but others come to the
surface in the night or during storms when the sunlight is absent.
Through this habit they are often thrown by the waves on the decks of
small vessels. Largely from Danish merchant-vessels, Dr. Lütken has
obtained the unrivaled collection of these sea-waifs preserved in the
Museum of the University of Copenhagen. The species are all small in
size and feeble in structure, the prey of the larger fishes of the
depths, from which their lantern-like spots and large eyes help them to
escape. The numerous species are now ranged in about fifteen genera,
although earlier writers placed them all in a single genus _Myctophum_
(_Scopelus_).
[Illustration:
FIG. 93.—Lantern-fish, _Myctophum opalinum_ Goode & Bean. Gulf Stream.
]
In the genus _Diaphus_ (_Æthoprora_) there is a large luminous gland on
the end of the short snout, like the headlight of an engine. In
_Dasyscopelus_ the scales are spinescent, but in most of the genera, as
in _Myctophum_, the scales are cycloid and caducous, falling at the
touch. In _Diaphus_ the luminous spots are crossed by a septum giving
them the form of the Greek letter θ (theta). One of the commonest
species is _Myctophum humboldti_.
[Illustration:
FIG. 94.—Lantern-fish, _Ceratoscopelus madeirensis_ (Lowe). Gulf
Stream.
]
=Chirothricidæ.=—The remarkable extinct family of _Chirothricidæ_ may be
related to the _Synodontidæ_, or _Myctophidæ_. In this group the teeth
are feeble, the paired fins much enlarged, and the ventrals are well
forward. The dorsal fin, inserted well forward, has stout basal bones.
_Chirothrix libanicus_ of the Cretaceous of Mt. Lebanon is remarkable
for its excessively large ventral fins. _Telepholis_ is a related genus.
_Exocœtoides_ with rounded caudal fin is probably the type of a distinct
family, _Exocœtoididæ_, the caudal fin being strongly forked in
_Chirothrix_. The small extinct group of _Rhinellidæ_ is usually placed
near the _Myctophidæ_. They are distinguished by the very long gar-like
jaws; whether they possessed adipose fins or luminous spots cannot be
determined. _Rhinellus furcatus_ and other species occur in the
Cretaceous of Europe and Asia. Fossil forms more or less distinctly
related to the _Myctophidæ_ are numerous. _Osmeroides monasterii_
(wrongly called _Sardinioides_), from the German Cretaceous, seems
allied to _Myctophum_, although, of course, luminous spots leave no
trace among fossils. _Acrognathus boops_ is remarkable for the large
size of the eyes.
[Illustration:
FIG. 95.—_Rhinellus furcatus_ Agassiz. Upper Cretaceous of Mt.
Lebanon. (After Woodward.)
]
=Maurolicidæ.=—The _Maurolicidæ_ are similar in form and habit, but
scaleless, and with luminous spots more highly specialized. _Maurolicus
pennanti_, the "Sleppy Argentine," is occasionally taken on either side
of the Atlantic. Other genera are _Zalarges_, _Vinciguerria_, and
_Valenciennellus_.
=The Lancet-fishes.=—The _Plagyodontidæ_ (_Alepisauridæ_) contains the
lancet-fishes, large, swift, scaleless fishes of the ocean depths with
very high dorsal fin, and the mouth filled with knife-like teeth. These
large fish are occasionally cast up by storms or are driven to the
shores by the torments of a parasite, _Tetrarhynchus_, found imbedded in
the flesh.
It is probable that they are sometimes killed by being forced above
their level by fishes which they have swallowed. In such cases they are
destroyed through the reduction of pressure.
Every part of the body is so fragile that perfect specimens are rare.
The dorsal fin is readily torn, the bones are very feebly ossified, and
the ligaments connecting the vertebræ are very loose and extensible, so
that the body can be considerably stretched. "This loose connection of
the parts of the body is found in numerous deep-sea fishes, and is
merely the consequence of their withdrawal from the pressure of the
water to which they are exposed in the depths inhabited by them. When
within the limits of their natural haunts, the osseous, muscular, and
fibrous parts of the body will have that solidity which is required for
the rapid and powerful movements of a predatory fish. That the fishes of
this genus (_Plagyodus_) belong to the most ferocious of the class is
proved by their dentition and the contents of their stomach." (Günther.)
Dr. Günther elsewhere observes: "From the stomach of one example have
been taken several octopods, crustaceans, ascidians, a young _Brama_,
twelve young boarfishes (_Capros_), a horse-mackerel, and one young of
its own species."
[Illustration:
FIG. 96.—Lancet-fish, _Plagyodus ferox_ (Lowe). New York.
]
The lancet-fish, _Plagyodus ferox_, is occasionally taken on either side
of the Atlantic and in Japan. The handsaw-fish, called _Plagyodus
æsculapius_, has been taken at Unalaska, off San Luis Obispo, and in
Humboldt Bay. It does not seem to differ at all from _Plagyodus ferox_.
The original type from Unalaska had in its stomach twenty-one lumpfishes
(_Eumicrotremus spinosus_). This is the species described from Steller's
manuscripts by Pallas under the name of _Plagyodus_. Another species,
_Plagyodus borcalis_, is occasionally taken in the North Pacific.
The _Evermannellidæ_ is a small family of small deep-sea fishes with
large teeth, distensible muscles, and an extraordinary power of
swallowing other fishes, scarcely surpassed by _Chiasmodon_ or
_Saccopharynx_. _Evermannella_ (_Odontostomus_, the latter name
preoccupied) and _Omosudis_ are the principal genera.
The _Paralepidæ_ are reduced allies of _Plagyodus_, slender, silvery,
with small fins and fang-like jaws. As in _Plagyodus_, the adipose fin
is developed and there are small luminous dots. The species are few and
mostly northern; one of them, _Sudis ringens_, is known only from a
single specimen taken by the present writer from the stomach of a hake
(_Merluccius productus_), the hake in turn swallowed whole by an
albacore in the Santa Barbara Channel. The _Sudis_ had been devoured by
the hake, the hake by the albacore, and the albacore taken on the hook
before the feeble _Sudis_ had been digested.
[Illustration:
FIG. 97.—_Eurypholis sulcidens_ Pictet, restored. Family
_Enchodontidæ_. Upper Cretaceous of Mt. Lebanon. (After Woodward, as
_E. boissieri_.)
]
Perhaps allied to the _Plagyodontidæ_ is also the large family of
_Enchodontidæ_, widely represented in the Cretaceous rocks of Syria,
Europe, and Kansas. The body in this group is elongate, the teeth very
strong, and the dorsal fin short. _Enchodus lewesiensis_ is found in
Mount Lebanon, _Halec sternbergi_ in the German Cretaceous, and many
species of _Enchodus_ in Kansas; _Cimolichthys dirus_ in North Dakota.
Remotely allied to these groups is the extinct family of _Dercetidæ_
from the Cretaceous of Germany and Syria. These are elongate fishes, the
scales small or wanting, but with two or more series of bony scutes
along the flanks. In _Dercetis scutatus_ the scutes are large and the
dorsal fin is very long. Other genera are _Leptotrachelus_ and
_Pelargorhynchus_. Dr. Boulenger places the _Dercetidæ_ in the order
_Heteromi_. This is an expression of the fact that their relations are
still unknown. Probably related to the _Dercetidæ_ is the American
family of _Stratodontidæ_ with its two genera, _Stradodus_ and _Empo_
from the Cretaceous (Niobrara) deposits of Kansas. _Empo nepaholica_ is
one of the best-known species.
[Illustration:
FIG. 98.—_Eurypholis freyeri_ Heckel. Family _Enchodontidæ_.
Cretaceous. (After Heckel; the restoration of the jaws incorrect.)
]
[Illustration:
FIG. 99.—_Argyropelecus olfersi_ Cuvier. Gulf Stream.
]
=The Sternoptychidæ.=—The _Sternoptychidæ_ differ materially from all
these forms in the short, compressed, deep body and distorted form. The
teeth are small, the body bright silvery, with luminous spots. The
species live in the deep seas, rising in dark or stormy weather.
_Sternoptyx diaphana_ is found in almost all seas, and species of
_Argyropelecus_ are almost as widely distributed. After the earthquakes
in 1896, which engulfed the fishing villages of Rikuzen, in northern
Japan, numerous specimens of this species were found dead, floating on
the water, by the steamer _Albatross_.
The _Idiacanthidæ_ are small deep-sea fishes, eel-shaped and without
pectorals, related to the _Iniomi_.
=Order Lyopomi.=—Other deep-sea fishes constitute the order or suborder
_Lyopomi_ (λυός, loose; πῶμα, opercle). These are elongate fishes having
no mesocoracoid, and the preopercle rudimentary and connected only with
the lower jaw, the large subopercle usurping its place. The group, which
is perhaps to be regarded as a degenerate type of _Isospondyli_,
contains the single family of _Halosauridæ_, with several species, black
in color, soft in substance, with small teeth and long tapering tail,
found in all seas. The principal genera are _Halosaurus_ and
_Aldrovandia_ (_Halosauropsis_). _Aldrovandia macrochira_ is the
commonest species on our Atlantic coast.
[Illustration:
FIG. 100.—_Aldrovandia gracilis_ (Goode & Bean). Guadaloupe Island,
West Indies. Family _Halosauridæ_.
]
Several fossil _Halosauridæ_ are described from the Cretaceous of Europe
and Syria, referred to the genera _Echidnocephalus_ and _Enchelurus_.
Boulenger refers the _Lyopomi_ to the suborder _Heteromi_.