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Subclass, TELEOSTEI. 
Order, TELEOCEPHALI. 
Suborder, ACANTHOPTERI. 
Family ETHEOSTOMATIDJE, (the Darters.) 
Genus PLEUROLEPIS, Agassiz. 
1. Pleurolepis pellucidus (Baird) Ag. Sand Darter, (M. V. 219., Nel- 
son, 35). 
Abundant in clear sandy streams, wherever such occur : therefore gen- 
erally absent in the prairie region, but occurring in the Wabash valley and 
in the northwestern part of the state. The genus Pleurolepis , like Ammo - 
crypta , has usually but one anal spine, although two have been generally 
ascribed to it. Pine Cr. and Bock B., in Ogle Co. 
2. Pleurolepis asprellus Jordan (sp. nov.) Bough Sand Darter. 
A species similar in form to P. pellucidus , but less transparent and 
much more completely scaled. The size is also much larger. 
Body very long and slender, nearly cylindrical, about as in P. pellu- 
cidus, the depth about 8 in the length. Caudal peduncle long and slender, 
its length nearly 4 times in total. Head long and rather slender, 4*- in 
length ; eyes very large, high up and very close together, shorter than 
snout, having considerable vertical range. 
Mouth not large, sub-terminal, horizontal, the upper jaw rather the 
longer. Upper jaw sub-protractile, the furrow separating it from the fore- 
head very distinct laterally, but obliterated mesially, the skin covering the 
middle of the intermaxillaries being continuous with that of the rest of the 
forehead. Cheeks, opercles and sides of the crown covered with pectinated 
scales ; opercular spine well developed. Teeth as usual, rather feeble. 
Squamation much more complete than in P. pellucidus. Sides and back 
with well-developed, closely imbricated scales, which are not imbedded as 
in P. pellucidus ; the scales larger on the caudal peduncle than anteriorly. 
Jugular region, and belly between ventrals and anal, entirely naked; spac- 
between bases of ventrals scaled ; back of neck scaly ; lateral line wells 
developed, with about 98 scales, 10 series above the lateral line. Fine 
large, the dorsals well separated, the spinous dorsal high, its anterior rays 
highest; second dorsal smaller and smaller than anal. Anal fin with a sin- 
gle rather flexible spine ; caudal lunate, more concave than usual in darters. 
Pectorals and ventrals large, their tips about even, neither quite reaching 
the vent. Coloration of smaller specimens much as in P. pellucidus, accord- 
