266 REPOKT OF STATE GEOLOGIST. 



AA. Pseudobrauchiie and air-bladder well developed ; preopercle ser- 

 rate; branchiostegals seven; adult size large (Percime). 

 a. No canine teeth ; scales along lateral line about 75. 



Perca, p. 284. 

 aa. Canine teeth present ; scales about 90 to 95. 



Stizostedion, p. 285. 



Genus AMMOCRYPTA Jordan. 



Small, delicate fishes with bodies nearly translucent during life. 

 Form long, slender, and nearly cylindrical. Head long. Mouth term- 

 inal and wide. Middle of the belly naked ; often with only a few scales 

 along the lateral line. Vomer with teeth. Anal spines one or two. 

 Lateral line developed. 



Ammocrypta pellucida (Baird). 

 Sand Darter. 



Jordan and Gilbert, 1882, 6", 489. 



Body elongated, slender and cylindrical. Head small, long and 

 pointed. Caudal peduncle slender. Depth in the length about nine. 

 Head in length about five. Mouth nearly horizontal, the maxillary 

 reaching back to front of eye. Gill-membranes united, but free from 

 the isthmus. Dorsal rays XI, 10. Anal rays I, 8. Considerable areas 

 of the body devoid of scales, as the middle of the belly, the region in 

 front of the spinous dorsal, and the chest. Five or six rows of feeble 

 scales along the lateral lines, about seventy-five in a row. A few scales 

 on cheeks and opercles, and a few "on the back of the neck. Celor in 

 life translucent, with a series of dark dots along the middle of the back 

 and another series on each side. Also a gilt band along each lateral line. 

 Fins pale. In alcoholic specimens, the general color is white. Reaches 

 a length of two and one-half inches. The variety darum (Jordan and 

 Meek, 33, '88, 49) differs in having no scales on the neck and few an- 

 teriorly, except the five or six rows close to the lateral line. 



Mississippi Valley from Pennsylvania to Minnesota, living in clear 

 sandy streams. Found probably throughout Indiana. Carroll County 

 {2S, '88, 49, variety darum); Marion County (i, '77, 44, 375); E. Fork 

 White River (£3, '84, 204); Logansport (i, '88, 159); Posey County 

 (4, '88, 164); Vigo County (16, 95); Eel River system (4, '94, 39). Dr. 

 Evermann informs me that the variety darum is also found in Vigo 

 County. 



This species has the habit of concealing itself in the sand at the bot- 

 tom of streams in such a way that only its eyes and snout are visible. 

 For an account of its habits see Jordan and Copeland, American Naturalist, 

 1877, 86. Forbes has studied the nature of its food. This consists of 

 the larvse of dipterous and neuropterous insects. 



