PERCOIDEA, OR PERCH-LIKE FISHES
=PERCOID Fishes.=—We may now take up the long series of the _Percoidea_,
the fishes built on the type of the perch or bass. This is a group of
fishes of diverse habits and forms, but on the whole representing better
than any other the typical _Acanthopterygian_ fish. The group is
incapable of concise definition, or, in general, of any definition at
all; still, most of its members are definitely related to each other and
bear in one way or another a resemblance to the typical form, the perch,
or more strictly to its marine relatives, the sea-bass, or _Serranidæ_.
The following analysis gives most of the common characters of the group:
Body usually oblong, covered with scales, which are typically ctenoid,
not smooth nor spinous, and of moderate size. Lateral line typically
present and concurrent with the back. Head usually compressed laterally
and with the cheeks and opercles scaly. Mouth various, usually terminal
and with lateral cleft; the teeth various, but typically pointed,
arranged in bands on the jaws, and in several families on the vomer and
palatine bones also, as well as on the pharyngeals; gill-rakers usually
sharp, stoutish, armed with teeth, but sometimes short or feeble; lower
pharyngeals almost always separate, usually armed with cardiform teeth;
third upper pharyngeal moderately enlarged, elongate, not articulated to
the cranium, the fourth typically present; gills four, a slit behind the
fourth; gill membranes free from the isthmus, and usually not connected
with each other; pseudobranchiæ typically well developed.
Branchiostegals few, usually six or seven. No bony stay connecting the
suborbital chain to the preopercle. Opercular bones all well developed,
normal in position; the preopercle typically serrate. No cranial spines.
Dorsal fin variously developed, but always with some spines in front,
these typically stiff and pungent; anal fin typically short, usually
with three spines, sometimes with a larger number, rarely with none;
caudal fin various, usually lunate; pectoral fins well developed,
inserted high; ventral fins always present, thoracic, separate, almost
always with one spine and five rays, the _Aphredoderidæ_ having more, a
few _Serranidæ_ having fewer. Air-bladder usually present, without
air-duct in adult; simple and generally adherent to the walls of the
abdomen. Stomach cæcal, with pyloric appendages, the intestines short in
most species, long in the herbivorous forms. Vertebral column well
developed, none of the vertebræ especially modified, the number 10 + 14
= 24, except in certain extratropical and fresh-water forms, which
retain primitive higher numbers. Shoulder-girdle normally developed, the
post-temporal bifurcate attached to the skull, but not coossified with
it; none of the epipleural bones attached to the center of the vertebræ;
coracoids normal, the hypercoracoid always with a median foramen, the
basal bones of the pectoral (actinosts or pterygials) normally
developed, three or four in number, hour-glass-shaped, longer than
broad; premaxillary forming the border of the mouth usually protractile;
bones of the mandible distinct. Orbitosphenoid wanting.
The most archaic of the perch-like types are apparently some of those of
the fresh waters. Among these the process of evolution has been less
rapid. In some groups, as the _Percidæ_, the great variability of
species is doubtless due to the recent origin, the characters not being
well fixed.
=The Pirate-perches: Aphredoderidæ.=—Among the most remarkable of the
living percoid fishes and probably the most primitive of all, showing
affinities with the _Salmopercæ_, is the pirate-perch, _Aphredoderus
sayanus_, a little fish of the lowland streams of the Mississippi
Valley. The family of _Aphredoderidæ_ agrees with the berycoid fishes in
scales and structure of the fins, and Boulenger places it with the
Berycidæ. Starks has shown, however, that it lacks the orbitosphenoid,
and the general osteology is that of the perch-like fishes. The dorsal
and anal have a few spines. The thoracic ventrals have one spine and
eight rays. There is no adipose fin and probably no duct to the
air-bladder. A singular trait is found in the position of the vent. In
the adult this is in front of the ventral fins, at the throat. In the
young it is behind the ventral fins as in ordinary fishes. With age it
moves forward by the prolongation of the horizontal part of the
intestine or rectum. The same peculiar position of the vent is found in
the berycoid genus _Paratrachichthys_.
[Illustration:
FIG. 228.—Pirate Perch, _Aphredoderus sayanus_ (Gilliams). Illinois
River.
]
[Illustration:
FIG. 229.—Everglade Pigmy Perch, _Elassoma evergladei_ Jordan.
Everglades of Florida.
]
In the family _Aphredoderidæ_ but one species is known, _Aphredoderus
sayanus_, the pirate-perch. It reaches a length of five inches and lives
in sluggish lowland streams with muddy bottom from New Jersey and
Minnesota to Louisiana. It is dull green in color and feeds on insects
and worms. It has no economic value, although extremely interesting in
its anatomy and relationship.
Whether the _Asineopidæ_, fresh-water fishes of the American Eocene, and
the _Erismatopteridæ_, of the same deposits (see page 235) are related
to _Aphredoderus_ or to _Percopsis_ is still uncertain.
[Illustration:
FIG. 230.—Skull of the Rock Bass, _Ambloplites rupestris_.
]
=The Pigmy Sunfishes: Elassomidæ.=—One of the most primitive groups is
that of _Elassomidæ_, or pigmy sunfishes. These are very small fishes,
less than two inches long, living in the swamps of the South, resembling
the sunfishes, but with the number of dorsal spines reduced to from
three to five. _Elassoma zonatum_ occurs from southern Illinois to
Louisiana. _Elassoma evergladei_ abounds in the Everglades of Florida.
In both the body is oblong and compressed, the color is dull green
crossed by black bars or blotches.
=The Sunfishes: Centrarchidæ.=—The large family of _Centrarchidæ_, or
sunfishes, is especially characteristic of the rivers of the eastern
United States, where the various species are inordinately abundant. The
body is relatively short and deep, and the axis passes through the
middle so that the back has much the same outline as the belly. The
pseudobranchiæ are imperfect, as in many fresh-water fishes, and the
head is feebly armed, the bones being usually without spines or
serratures. The colors are often brilliant, the sexes alike, and all are
carnivorous, voracious, and gamy, being excellent as food. The origin of
the group is probably Asiatic, the fresh-water serranoid of Japan,
_Bryttosus_, resembling in many ways an American sunfish, and the genus
_Kuhlia_ of the Pacific showing many homologies with the black bass,
_Micropterus_.
[Illustration:
FIG. 231.—Crappie, _Pomoxis annularis_ Rafinesque. Ohio River.
]
[Illustration:
FIG. 232.—Crappie, _Pomoxis annularis_ (Raf.). (From life by Dr. R. W.
Shufeldt.)
]
[Illustration:
FIG. 233.—Rock Bass, _Ambloplites rupestris_ (Rafinesque.) Ecorse,
Mich.
]
[Illustration:
FIG. 234.—Banded Sunfish, _Mesogonistius chætodon_ (Baird). Delaware
River.
]
=Crappies and Rock Bass.=—_Pomoxis annularis_, the crappie, and _Pomoxis
sparoides_, the calico-bass, are handsome fishes, valued by the angler.
These are perhaps the most primitive of the family, and in these species
the anal fin is larger than the dorsal. The flier, or round bass,
_Centrarchus macropterus_, with eight anal spines, is abundant in swamps
and lowland ponds of the Southern States. It is a pretty fish,
attractive in the aquarium. _Acantharchus pomotis_ is the mud-bass of
the Delaware, and _Archoplites interruptus_, the "perch" of the
Sacramento. The latter is a large and gamy fish, valued as food and
interesting as being the only fresh-water fish of the nature of perch or
bass native to the west of the Rocky Mountains. The numbers of this
species, according to Mr. Will S. Green of Colusa, California, have been
greatly reduced by the introduction of the catfish (_Ameiurus
nebulosus_) into the Sacramento. The perch eats the young catfish, and
its stomach is torn by their sharp pectoral spines. Another species of
this type is the warmouth (_Chænobryttus gulosus_) of the ponds of the
South, and still more familiar rock-bass or redeye (_Ambloplites
rupestris_) of the more northern lakes and rivers valued as a game-and
food-fish. A very pretty aquarium fish is the black-banded sunfish,
_Mesogonistius chætodon_, of the Delaware, as also the nine-spined
sunfish, _Enneacanthus gloriosus_, of the coast streams southward.
_Apomotis cyanellus_, the blue-green sunfish or little redeye, is very
widely distributed from Ohio westward, living in every brook. The
dissection of this species is given on page 26, Vol. I. To _Lepomis_
belong numerous species having the opercle prolonged in a long flap
which is always black in color, often with a border of scarlet or blue.
The yellowbelly of the South (_Lepomis auritus_), ear-like the showily
colored long-eared sunfish (_Lepomis megalotis_) of the southwest,
figured on page 2, Vol. I, the bluegill (_Lepomis pallidus_), abundant
everywhere south and west of New York, are members of this genus. The
genus _Eupomotis_ differs in its larger pharyngeals, which are armed
with blunt teeth. The common sunfish, or pumpkinseed, _Eupomotis
gibbosus_, is the most familiar representative of the family, abounding
everywhere from Minnesota to New England, then south to Carolina on the
east slope of the Alleghanies, breeding everywhere in ponds and in the
eddies of the clear brooks.
[Illustration:
FIG. 235.—Blue-Gill, _Lepomis pallidus_ (Mitchill). Potomac River.
]
[Illustration:
FIG. 236.—Long-eared Sunfish, _Lepomis megalotis_ (Rafinesque). From
Clear Creek, Bloomington, Indiana. Family _Centrarchidæ_.
]
[Illustration:
FIG. 237.—Common Sunfish, _Eupomotis gibbosus_ (Linnæus). Root River,
Wis.
]
=The Black Bass.=—The black bass (_Micropterus_) belong to the same
family as the sunfish, differing in the larger size, more elongate form,
and more voracious habit. The two species are among the most important
of American game-fishes, abounding in all clear waters east of the
Alleghanies and resisting the evils of civilization far better than the
trout.
The small-mouthed black bass, _Micropterus dolomieu_, is the most
valuable of the species. Its mouth, although large, is relatively small,
the cleft not extending beyond the eye. The green coloration is broken
in the young by bronze cross-bands. The species frequents only running
streams, preferring clear and cold waters, and it extends its range from
Canada as far to the southward as such streams can be found. Dr. James
A. Henshall, an accomplished angler, author of the "Book of the Black
Bass," says: "The black bass is eminently an American fish; he has the
faculty of asserting himself and of making himself completely at home
wherever placed. He is plucky, game, brave, unyielding to the last when
hooked. He has the arrowy rush and vigor of a trout, the untiring
strength and bold leap of a salmon, while he has a system of fighting
tactics peculiarly his own. I consider him inch for inch and pound for
pound the gamest fish that swims."
In the same vein Charles Hallock writes: "No doubt the bass is the
appointed successor of the trout; not through heritage, nor selection,
nor by interloping, but by foreordination. Truly, it is sad to
contemplate, in the not distant future, the extinction of a beautiful
race of creatures, whose attributes have been sung by all the poets; but
we regard the inevitable with the same calm philosophy with which the
astronomer watches the burning out of a world, knowing that it will be
succeeded by a new creation. As we mark the soft varitinted flush of the
trout disappear in the eventide, behold the sparkle of the coming bass,
as he leaps in the morning of his glory! We hardly know which to admire
the most—the velvet livery and the charming graces of the departing
courtier, or the flash of the armor-plates of the advancing warrior. The
bass will unquestionably prove himself a worthy substitute for his
predecessor and a candidate for a full legacy of honors.
"No doubt, when every one of the older states shall become as densely
settled as Great Britain itself, and all the rural aspects of the
crowded domain resemble the suburban surroundings of our Boston; when
every feature of the pastoral landscape shall wear the finished
appearance of European lands, and every verdant field be closely cropped
by lawn-mowers and guarded by hedges, and every purling stream which
meanders through it has its water-bailiff, we shall still have speckled
trout from which the radiant spots have faded, and tasteless fish, to
catch at a dollar a pound (as we already have on Long Island), and all
the appurtenances and appointments of a genuine English trouting
privilege and a genuine English 'outing.'
[Illustration:
FIG. 238.—Small Mouth Black Bass, _Micropterus dolomieu_ Lacépède.
]
"In those future days, not long hence to come, some venerable piscator,
in whose memory still lingers the joy of fishing, the brawling stream
which tumbled over the rocks in the tangled wildwood, and moistened the
arbutus and the bunchberries which garnished its banks, will totter
forth to the velvet edge of some peacefully flowing stream, and having
seated himself on a convenient point in a revolving easy-chair, placed
there by his careful attendant, cast right and left for the semblance of
sport long dead.
"Hosts of liver-fed fish rush to the signal for their early morning
meal, and from the center of the boil which follows the fall of the
handfuls thrown in my piscator of the ancient days will hook a two-pound
trout, and play him hither and yon, from surface to bottom, without
disturbing the pampered gourmands which are gorging themselves upon the
disgusting viands; and when he has leisurely brought him to land at
last, and the gillie has scooped him with his landing-net, he will feel
in his capacious pocket for his last trade dollar, and giving his friend
the tip, shuffle back to his house, and lay aside his rod forever."
The black bass is now introduced into the streams of Europe and
California. There is little danger that it will work injury to the
trout, for the black bass prefers limestone streams, and the trout
rarely does well in waters which do not flow over granite rock or else
glacial gravel.
The large-mouth black bass (_Micropterus salmoides_) is very much like
the other in appearance. The mouth is larger, in the adult cleft beyond
the eye; the scales are larger, and in the young there is always a broad
black stripe along the sides and no cross-bands. The two are found in
the same region, but almost never in the same waters, for the
large-mouth bass is a fish of the lakes, ponds, and bayous, always
avoiding the swift currents. The young like to hide among weeds or
beneath lily-pads. From its preference for sluggish waters, its range
extends farther to the southward, as far as the Mexican State of
Tamaulipas.
_Plioplarchus_ is a genus of fossil sunfishes from the Eocene of South
Dakota and Oregon. _Plioplarchus sexspinosus_, _septemspinosus_, and
_whitei_ are imperfectly known species.
=The Saleles: Kuhliidæ.=—Much like the sunfishes in anatomy, though more
like the white perch in appearance and habit, are the members of the
little family of _Kuhliidæ_. These are active silvery perches of the
tropical seas, ponds, and river-mouths, especially abundant in
Polynesia. _Kuhlia malo_ is the aholehole of the Hawaiians, a silvery
fish living in great numbers in brackish waters. _Kuhlia rupestris_, the
salele of the Samoan rivers, is a large swift fish of the rock pools, in
form, color, and habits remarkably like the black bass. It is silvery
bronze in hue, everywhere mottled with olive-green. The sesele, _Kuhlia
marginata_, lives with it in the rivers, but is less abundant. The
saboti, _Kuhlia tæniura_, a large silvery fish with cross-bands on the
caudal fin, lives about lava-rooks in Polynesia from the Galapagos to
Samoa and the East Indies, never entering rivers. Still other species
are found in the rock pools and streams of Japan and southward.
The skeleton in _Kuhlia_ is essentially like that of the black bass, and
Dr. Boulenger places the genus with the _Centrarchidæ_.
=The True Perches: Percidæ.=—The great family of _Percidæ_ includes
fresh-water fishes of the northern hemisphere, elongate in body, with
the vertebræ in increased number and with only two spines in the anal
fin. About ninety species are recorded, the vast majority being
American. The dwarf perches, called darters (_Etheostominæ_), are
especially characteristic of the clear streams to the eastward of the
plains of the Missouri. These constitute one of the greatest attractions
of our American river fauna. They differ from the perch and its European
allies in their small size, bright colors, and large fins, and more
technically in the rudimentary condition of the pseudobranchiæ and the
air-bladder, both of which organs are almost inappreciable. The
preopercle is unarmed, and the number of the branchiostegals is six. The
anal papilla is likewise developed, as in the _Gobiidæ_, to which group
the darters bear a considerable superficial resemblance, which, however,
indicates no real affinity.
[Illustration:
FIG. 239.—Large-mouthed Black Bass, _Micropterus salmoides_ (Lac.).
(From life by Dr. R. W. Shufeldt.)
]
=Relations of Darters to Perches.=—The colors of the _Etheostominæ_, or
darters, are usually very brilliant, species of _Etheostoma_ especially
being among the most brilliantly colored fishes known; the sexual
differences are often great, the females being, as a rule, dull in color
and more speckled or barred than the males. Most of them prefer clear
running water, where they lie on the bottom concealed under stones,
darting, when frightened or hungry, with great velocity for a short
distance, by a powerful movement of the fan-shaped pectorals, then
stopping as suddenly. They rarely use the caudal fin in swimming, and
they are seldom seen floating or moving freely in the water like most
fishes. When at rest they support themselves on their expanded ventrals
and anal fin. All of them can turn the head from side to side, and they
frequently lie with the head in a curved position or partly on one side
of the body. The species of _Ammocrypta_, and perhaps some of the
others, prefer a sandy bottom, where, by a sudden plunge, the fish
buries itself in the sand, and remains quiescent for hours at a time
with only its eyes and snout visible. The others lurk in stony places,
under rocks and weeds. Although more than usually tenacious of vitality,
the darters, from their bottom life, are the first to be disturbed by
impurities in the water. All the darters are carnivorous, feeding
chiefly on the larvæ of _Diptera_, and in their way voracious. All are
of small size; the largest (_Percina rex_) reaches a length of ten
inches, while the smallest (_Microperca punctulata_) is, one of the
smallest spiny-rayed fishes known, barely attaining the length of an
inch and a half. In Europe no _Etheostominæ_ are found, their place
being filled by the genera _Zingel_ and _Aspro_, which bear a strong
resemblance to the American forms, a resemblance which may be a clue to
the origin of the latter.
=The Perches.=—The European perch, _Perca fluviatilis_, is placed by
Cuvier at the head of the fish series, as representing in a high degree
the traits of a fish without sign of incomplete development on the one
hand or of degradation on the other. Doubtless the increased number of
the vertebræ is the chief character which would lead us to call in
question this time-honored arrangement. Because, however, the perch has
a relatively degenerate vertebral column, we have used an allied form,
the striped bass, as a fairer type of the perfected spiny-rayed fish.
Certainly the bass represents this type better than the perch.
But though we may regard the perch as nearest the typically perfect
fish, it is far from being one of the most highly specialized, for, as
we have seen in several cases, a high degree of specialization of a
particular structure is a first step toward its degradation.
The perch of Europe is a common game-fish of the rivers. The yellow
perch of America (_Perca flavescens_) is very much like it, a little
brighter in color, olive and golden with dusky cross-bands. It frequents
quiet streams and ponds from Minnesota eastward, then southward east of
the Alleghanies. "As a still-pond fish," says Dr. Charles Conrad Abbott,
"if there is a fair supply of spring-water, they thrive excellently; but
the largest specimens come either from the river or from the inflowing
creeks. Deep water of the temperature of ordinary spring-water, with
some current and the bed of the stream at least partly covered with
vegetation, best suits this fish." The perch is a food-fish of moderate
quality. In spite of its beauty and gaminess, it is little sought for by
our anglers, and is much less valued with us than is the European perch
in England. But Dr. Goode ventures to prophesy that "before many years
the perch will have as many followers as the black bass among those who
fish for pleasure" in the region it inhabits. "A fish for the people it
is, we will grant, and it is the anglers from among the people who have
neither time nor patience for long trips nor complicated tackle who will
prove its steadfast friends." The boy values it, according to Thoreau.
When he returns from the mill-pond, he numbers his perch as "real
fishes." "So many unquestionable fish he counts, and so many chubs,
which he counts, then throws away."
[Illustration:
FIG. 240.—Yellow Perch, _Perca flavescens_ Mitchill. Potomac River.
]
In the perch, the oral valves, characteristic of all bony fishes, are
well developed. These structures recently investigated by Evelyn G.
Mitchill, form a fold of connective tissue just behind the premaxillary
and before the vomer. They are used in respiration, preventing the
forward flow of water as the mouth closes.
Several perch-like fishes are recorded as fossils from the Miocene.
Allied to the perch, but long, slender, big-mouthed, and voracious, is
the group of pike perches, found in eastern America and Europe. The
wall-eye, or glass-eye (_Stizostedion vitreum_), is the largest of this
tribe, reaching a weight of ten to twenty pounds. It is found throughout
the region east of the Missouri in the large streams and ponds, an
excellent food-fish, with white, flaky flesh and in the north a game
fish of high rank. The common names refer to the large glassy eye,
concerning which Dr. Goode quotes from some "ardent admirer" these
words: "Look at this beautiful fish, as symmetrical in form as the
salmon. Not a fault in his make-up, not a scale disturbed, every fin
perfect, tail clean-cut, and his great, big wall-eyes stand out with
that life-like glare so characteristic of the fish."
[Illustration:
FIG. 241.—Sauger, _Stizostedion canadense_ (Smith). Ecorse, Mich.
]
Similar to the wall-eye, but much smaller and more translucent in color,
is the sauger, or sand-pike, of the Great Lakes and Northern rivers,
_Stizostedion canadense_. This fish rarely exceeds fifteen inches in
length, and as a food-fish it is of correspondingly less importance.
[Illustration:
FIG. 242.—The Aspron, _Aspro asper_ (Linnæus). Rhone River. Family
_Percidæ_. (After Seelye.)
]
The pike-perch, or zander, of central Europe, _Centropomus_ (or
_Sandrus_) _lucioperca_, is an excellent game-fish, similar to the
sauger, but larger, characterized technically by having the ventral fins
closer together. Another species, _Centropomus volgensis_, in Russia,
looks more like a perch than the other species do. _Sandroserrus_, a
fossil pike-perch, occurs in the Pliocene. Another European fish related
to the perch is the river ruff, or pope, _Acerina cernua_, which is a
small fish with the form of a perch and with conspicuous mucous cavities
in the skull. It is common throughout the north of Europe and especially
abundant at the confluence of rivers. _Gymnocephalus schrætzer_ of the
Danube has the head still more cavernous. _Percarina demidoffi_ of
southern Russia is another dainty little fish of the general type of the
perch. A fossil genus of this type called _Smerdis_ is numerously
represented in the Miocene and later rocks. The aspron, _Aspro asper_,
is a species like a darter found lying on the bottoms of swift rivers,
especially the Rhone. The body is elongate, with the paired fins highly
developed. _Zingel zingel_ is found in the Danube, as is also a third
species called _Aspro streber_. In form and coloration these species
greatly resemble the American darters, and the genus _Zingel_ is,
perhaps, the ancestor of the entire group. _Zingel_ differs from
_Percina_ mainly in having seven instead of six branchiostegals and the
pseudobranchiæ better developed. The differences in these and other
regards which distinguish the darters are features of degradation, and
they are also no doubt of relatively recent acquisition. To this fact we
may ascribe the difficulty in finding good generic characters within the
group. Sharply defined genera occur where the intervening types are
lost. The darter is one of the very latest products in the evolution of
fishes.
[Illustration:
FIG. 243.—The Zingel, _Zingel zingel_ (Linnæus). Danube River. (After
Seelye.)
]
=The Darters: Etheostominæ.=—Of the darters, or etheostomine perches,
over fifty species are known, all confined to the streams of the region
bounded by Quebec, Assiniboia, Colorado, and Nuevo Leon. All are small
fishes and some of them minute, and some are the most brilliantly
colored of all fresh-water fishes of any region, the most ornate
belonging to the large genus called _Etheostoma_. The largest species,
the most primitive because most like the perch, belong to the genus
_Percina_.
First among the darters because largest in size, most perch-like in
structure, and least degenerate, we place the king darter, _Percina rex_
of the Roanoke River in Virginia. This species reaches a length of six
inches, is handsomely colored, and looks like a young wall-eye.
[Illustration:
FIG. 244.—Log-perch, _Percina caprodes_ (Rafinesque). Licking Co.,
Ohio.
]
The log-perch, _Percina caprodes_, is near to this, but a little
smaller, with the body surrounded by black rings alternately large and
small. In this widely distributed species, large enough to take the
hook, the air-bladder is present although small. In the smaller species
it vanishes by degrees, and in proportion as in their habits they cling
to the bottom of the stream. The air-bladder is least developed in those
species which cling closest to the bottom of the stream.
[Illustration:
FIG. 245.—Black-sided Darter, _Hadropterus aspro_ (Cope & Jordan).
Chickamauga River.
]
The genus _Hadropterus_ includes many handsome species, most of them
with a black lateral band widened at intervals. The black-sided darter,
_Hadropterus aspro_, is the best-known species and one of the most
elegant of all fishes, abounding in the clear gravelly streams of the
Ohio basin and northwestward.
_Hadropterus evides_ of the Ohio region is still more brilliant, with
alternate bands of dark blue-green and orange-red, most exquisite in
their arrangement. In the South, _Hadropterus nigrofasciatus_, the
crawl-a-bottom of the Georgia rivers, is a heavily built darter, which
Vaillant has considered the ancestral species of the group. Still more
swift in movement and bright in color are the species of _Hypohomus_,
which flash their showy hues in the sparkling brooks of the Ozark and
the Great Smoky Mountains. _Hypohomus aurantiacus_ is the best-known
species.
[Illustration:
FIG. 246.—Green-sided Darter, _Diplesion blennioides_ Rafinesque.
Clinch River. Family _Percidæ_.
]
_Diplesion blennioides_, the green-sided darter, is the type of numerous
species with short heads, large fins, and coloration of speckled green
and golden. It abounds in the streams of the Ohio Valley.
[Illustration:
FIG. 247.—Tessellated Darter, _Boleosoma olmstedi_ (Storer). Potomac
River.
]
The tessellated darters, _Boleosoma_, are the most plainly colored of
the group and among the smallest; yet in the delicacy, wariness, and
quaintness of motion they are among the most interesting, especially in
the aquarium. _Boleosoma_ _nigrum_, the Johnny darter in the West, and
_Boleosoma olmstedi_ in the East are among the commonest species, found
half hidden in the weeds of small brooks, and showing no bright colors,
although the male in the spring has the head, and often the whole body,
jet black.
[Illustration:
FIG. 248.—Crystal Darter, _Crystallaria asprella_ (Jordan). Wabash
River.
]
_Crystallaria asprella_, a large species almost transparent, is
occasionally taken in swift currents along the limestone banks of the
Mississippi. Still more transparent is the small sand-darter,
_Ammocrypta pellucida_, which lives in the clearest of waters,
concealing itself by plunging into the sand. Its scales are scantily
developed, as befits a fish that chooses this method of protection, and
in the related _Ammocrypta beani_ of the streams of the Louisiana
pine-woods, the body is almost naked, as also in _Ioa vitrea_, the
glassy darter of the pine-woods of North Carolina.
[Illustration:
FIG. 249.—Sand-darter, _Ammocrypta clara_ (Jordan & Meek). Des Moines
River.
]
In the other darters the body is more compressed, the movements less
active, the coloration even more brilliant in the males, which are far
more showy than their dull olivaceous mates.
To _Etheostoma_ nearly half of the species belong, and they form indeed
a royal series of little fishes. Only a few can be noticed here, but all
of them are described in detail and many are figured by Jordan and
Evermann ("Fishes of North and Middle America," Vol. I).
[Illustration:
FIG. 250.—_Etheostoma jordani_ Gilbert. Chestnut Creek, Verbena, Ala.
]
[Illustration:
FIG. 251.—Blue-breasted Darter, _Etheostoma camurum_ (Cope), the most
brilliantly colored of American river fishes. Cumberland Gap, Tenn.
]
Most beautiful of all fresh-water fishes is the blue-breasted darter,
_Etheostoma camurum_, red-blue and olive, with red spots, like a trout.
This species lives in clear streams of the Ohio valley, a region perhaps
to be regarded as the center of abundance of these fishes.
Very similar is the trout-spotted darter, _Etheostoma maculatum_, dusky
and red, with round crimson spots. _Etheostoma rufilineatum_ of the
French Broad is one of the most gaudy of fishes. _Etheostoma australe_
of Chihuahua ranges farthest south of all the darters, and _Etheostoma
boreale_ of Quebec perhaps farthest north, though _Etheostoma iowæ_,
found from Iowa to the Saskatchewan, may dispute this honor. _Etheostoma
cæruleum_, the rainbow darter or soldier-fish, with alternate oblique
bands of blue and scarlet, is doubtless the most familiar of the
brilliantly colored species, as it is the most abundant throughout the
Ohio valley.
_Etheostoma flabellare_, the fan-tailed darter, discovered by Rafinesque
in Kentucky in 1817, was the first species of the series made known to
science. It has no bright colors, but its movements in water are more
active than any of the others, and it is the most hardy in the aquarium.
_Psychromaster tuscumbia_ abounds in the great limestone springs of
northern Alabama, while _Copelandellus quiescens_ swarms in the
black-water brooks which flow into the Dismal Swamp and thence southward
to the Suwanee. It is a little fish not very active, its range going
farther into the southern lowlands than any other. Finally, _Microperca
punctulata_, the least darter, is the smallest of all, with fewest
spines and dullest colors, most specialized in the sense of being least
primitive, but at the same time the most degraded of all the darters.
No fossil forms nearly allied to the darters are on record. The nearest
is perhaps _Mioplosus labracoides_ from the Eocene at Green River,
Wyoming. This elongate fish, a foot long, has the dorsal rays IX-1, 13,
and the anal rays II, 13, its scales finely serrated, and the preopercle
coarsely serrated on the lower limb only. This species, with its
numerous congeners from the Rocky Mountain Eocene, is nearer the true
perch than the darters. Several species related to Perca are also
recorded from the Eocene of England and Germany. A species called
_Lucioperca skorpili_, allied to _Centropomus_, is described from the
Oligocene of Bulgaria, besides several other forms imperfectly
preserved, of still more doubtful affinities.