CHAPTER XVIII

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_.

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.

=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_.

=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.

=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.'

"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.

=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."

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."

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.

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.

=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.

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.

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.

_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.

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.

_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.

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).

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.