AMMOCRYPTA — SAND DARTERS 301 



ration of ventrals slightly less than their width at base. Scales 8-10, 89-97, 

 9-11 [12-16]; lateral line nearly straight, 2 to 12 pores usually lacking; cheeks 

 naked or with a trace of scales, or about half covered with very thin scattered 

 scales, a few of which may be pectinate; opercles with a few pectinate scales 

 on upper portion; nape scaled; throat, breast, and belly naked excepting 

 (sometimes) a portion or all of the space in front of the ventral fins directly 

 under pelvic girdle. 



A medium-sized and singularly interesting species, first 

 discovered in this state in a rocky creek of the Mississippi bluffs 

 in Hancock county, and since taken from the Rock River at 

 Cleveland, Erie, and Milan, from the Little Wabash at Effing- 

 ham, and from the Mississippi at East Dubuque, in the north- 

 western part of the state. Elsewhere it comes from Grosse 

 Isle, Mich., from the Detroit River, from the Ohio River at 

 Rising Sun, from the Wabash as far northward as Terre Haute, 

 and from a few points in Tennessee, Kentucky, Alabama, and 

 Arkansas. It is found chiefly in the swift currents of the larger, 

 clearer streams, but apparently is a rare fish everywhere, and 

 but little known. 



AMMOCRYPTA Jordan 



SAND DARTERS 



Body slender and elongate, subcylindrical; pellucid in life; mouth rather 

 wide, horizontal; premaxillaries protractile; teeth on vomer; vertebrae (pel- 

 lucida) 44 (23 + 21), (vivax) 41 (21 -f- 20); pyloric caeca 4. Extremely 

 slender fishes, with the habit of burying themselves in the sand; size moderate, 

 about 3 inches in length; 2 species known. 



AMMOCRYPTA PELLUCIDA (Baird) 



SAND DARTER 

 (Map XCII) 



Agassiz, 1863, Bull. Mus. Comp. Zool., I, 5 (Pleurolepis). 



J. & G., 489; M. V., 122 (Etheostoma) ; B., I, 102; J. & E., I, 1062; N., 35 (Pleuro- 

 lepis); J., 38 (Pleurolepis); F., 66; L., 28. 



Slender, cylindrical, pellucid fishes, with the premaxillaries protractile 

 and the appearance of Boleosoma rather than Crystallaria and Hadropterus, 

 and probably more nearly related to that genus than to the others. Length 

 2}>£ inches; body subcylindrical, scarcely deeper than wide, the sides slightly 

 flattened along their median line; depth 8.2 to 10.1 in length; caudal peduncle 

 slender, its depth 3.4 to 4.2 in its length. Color "translucent; scales with 

 fine black dots; a series (14 or 15) of small, squarish olive or bluish blotches 

 along the back and another along each side; lateral spots connected by a gill- 



