Percoidea, or Perch-like Fishes 215 
the rainbow darter or soldier-fish, with alternate oblique bands 
ef blue and scarlet, is doubtless the most familiar of the bril- 
liantly 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 move- 
ments 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, must 
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 Mzoplosus labracoides from the Eocene at 
Green River, Wyoming. This elongate fish, a foot long, has 
the dorsal rays [X--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 skorpilt, allied to Centropomus, is described from 
the Oligocene of Bulgaria, besides several other forms imper- 
fectly preserved, of still more doubtful affinities. 
