122 TELEOSTEI: ACANTHOPTERI. — XX. 
tion. Thus Etheostoma is to be explained by the hypothesis of 
the progressive adaptation of the young of certain Percine to a 
peculiar place of refuge and a peculiarly situated food supply. 
These are the mountaineers among fishes. Forced from the popu- 
lous and fertile valleys of the river beds and lake bottoms, they 
have taken refuge from their enemies in the rocky highlands, where 
the free waters play in ceaseless torrents, and there they have 
wrested from stubborn nature a meagre living. Although diminished 
in size by their constant struggle with the elements, they have de- 
veloped an activity and hardihood, a vigor of life and a glow of 
high color, almost unknown among the easier livers of the lower 
lands. Notwithstanding their trivial size, they do not seem to be 
dwarfed so much as concentrated fishes.” 
Their colors are often very brilliant, the males of some species 
being among the most brilliant fishes known. The sexes are usually 
unlike; the females being generally dull and speckled. They 
usually 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 movement of the large pec- 
torals, then stopping as suddenly. They rarely leave the bottom, 
and are never seen suspended in the water. A few species prefer 
a sandy bottom, where they lie buried in the sand, with only the 
eyes visible. The Darters feed chiefly on the larva of Diptera. 
The largest reach a length of 8 inches, but the average is about 24 
inches. (The name Etheostoma is said by Rafinesque to mean 
“ various mouths ” (repos, various ; oréua, mouth ?), the three species 
known to him caprodes, blennioides, and flabellare, differing much 
in this respect.) 
a, Body extremely elongate, hyaline, subterete, the belly mostly naked; 
lateral line complete; head, long, pointed; gill membranes somewhat 
united, 
6. Premaxillaries protractile; dorsal spines 7 to 11. 
c, Anal spine single; A. nearly as large as 24 D. (Ammocrypta! 
Jordan = Pleurolepis Baird.) 
d, Cheeks and opercles scaly. 
322, E. pellucidum Baird: Sanp Darrer. Scales of body 
not very rough, only those along lateral line and on tail well imbri- 
cated; nape thinly scaled, becoming usually wholly naked on median 
line; belly naked; maxillary barely reaching the large eye; P. 
short. Translucent, finely dotted above; a series of small square 
olive blotches along back, and another along lateral line, the latter 
connected by agilt band; fins pale. Head 4}; depth7. D.X~-10. 
A. I, 8 Scales 6-75-X. Vert. 44. L. 2}. Ohio Valley and 
N. W., abounding in clear sandy streams, where it buries itself in 
the sand by a sudden plunge, and lies with only the eyes uncovered. 
1 dupos, sand ; xpumrds, concealed. 
