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.
CHAPTER XIX
THE BASS AND THEIR RELATIVES
The Cardinal-fishes. Apogonidæ.—The Apogonidæ or cardinal-fishes are perch-like fishes, mostly of small size, with two distinct short dorsal fins. They are found in the warm seas, and many of them enter rivers, some even inhabiting hot springs. Many of the shore species are bright red in color, usually with black stripes, bands, or spots. Still others, however, are olive or silvery, and a few in deeper water are violet-black.
Fig. 252.—Cardinal-fish, Apogon retrosella Gill. Mazatlan.