AMMOCRYPTA SAND DARTERS 301 



cent, of second); caudal lunate; anal I, 13 op 14; pectorals 1.1 to 1.3 

 in head; separation 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 pecti- 

 nate; 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 discov- 

 ered 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 Effingham, and from the Missis- 

 sippi at East Dubuque, in the northwestern part of the state. Else- 

 where 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, Ala- 

 bama, 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; ver- 

 tebra; (pellucida) 44 (23+21), (vivax) 41 (21 + -20); pyloric ceeca 4. Ex- 

 tremely 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) 



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



J. & G., 489; M. V., 122 (Etheostoma) ; B., I, 102; J. & E., I, 1062; X., 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 Hadrop- 

 lerus, 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 IS) of 

 small, squarish olive or bluish blotches along the back and another 

 along each side; lateral spots connected by a gill-band " (Jordan and 



