302 FISHES OF ILLINOIS 



Evermann). Head 4.1 to 4 . 4 in length, its width 2 to 2 . 5 in its length; 

 interorbital space narrow, concave, 7.1 to 8.4 in head; eye 3.6 to 4.3; 

 nose decurved, pointed, 3.1 to 3 . 8 in head; mouth moderate, maxillary 

 extending to front of orbit; cleft 3.1 to 4.4 in head; lower jaw slightly 

 shorter than upper; gill-membranes somewhat connected, but forming a 

 sharp angle, the distance from muzzle to angle about 1J times that to 

 back of orbit. Dorsal fin IX-XI, 9-11 (usually IX or X); spinous and 

 soft portions widely separated, the space greater than width of eye; 

 height of first dorsal low, 2 . 2 to 3 . 5 (usually less than 3) in head, second 

 1 . 8 to 2 . 1 (height of first 56 to 80 per cent, of second) ; caudal fin lunate; 

 anal I, 8 or 9 (occasionally 7); pectorals 1 to 1 .3 in head; separation of 

 ventrals less than the width at base. Scales 6 or 7, 67-78, 8 or 9+, the 

 upper and lower rows (nearest back and belly) sometimes lacking, body 

 being naked except for a strip along the side of varying width ; lateral 

 line usually complete; cheeks and opercles scaled; nape scaled or naked; 

 throat, breast, and bellv entirely naked; all scales more or less embedded 

 and with edges little ctenoid. 



Fig. 72 



This extremely interesting fish,. peculiar in its very slender form, 

 its semitransparent body, and its habit of living much of the time 

 in the sand, with only its eyes showing at the surface, make it one of 

 the most remarkable cases of special adaptation in this highly adap- 

 tive little group. Situations favorable to its habits are so rare in Illi- 

 nois that its comparative scarcity here was to be expected. It has 

 been found by us twenty-nine times, in localities well distributed— 

 twelve of them from the Wabash Valley, one from the lower Kas- 

 kaskia, six on streams of the lower Illinois, one on a creek of the 

 Mississippi bluffs, and three on Rock River or its tributaries. It is 

 reported by Jordan and Evermann from Lake Erie to Minnesota., 

 Kentucky, and Texas, occurring usually in clear sandy streams. 



An excellent account of its habits and peculiarities is given in 

 Bulletin 47 of the United States National Museum by Jordan and 

 Copeland. The fish has a very sharp nose with an exceedingly slim 

 and round body, as transparent as jelly but hard and firm to the 

 touch Its belly and much of its back are quite bare of scales, and 



