160 FISHES OF ILLINOIS 



stones. A few case-worms (Phyrganeidce) occurring in some 

 similar situations were the only other important element of the 

 food, of which insects made practically 98 per cent. Its small 

 inferior mouth, provided with fleshy lips something like those 

 of a sucker, enables this minnow to collect readily its peculiar 

 food, in respect to which, as well as in its favorite haunts, 

 it bears a considerable resemblance to the darters. In the 

 aquarium it rests, like a darter, upon the sand, supported by its 

 pectoral fins, the head moving gently up and down with the 

 opening and closing of the gills. 



Females greatly distended with eggs were taken by us in late 

 May and early June. Spring males are profusely but rather 

 minutely tuberculate on the top of the head, on the opercles, 

 and on the back and upper part of the sides to the posterior end 

 of the dorsal fin. 



Genus RHINICHTHYS Agassiz 



Body elongate, little compressed; mouth small, subinferior; upper jaw 

 not protractile, the upper mesially continuous with the skin of the forehead; a 

 small barbel at tip of maxillary; teeth 1 or 2, 4-4, 1 or 2, hooked and without 

 grinding surface; intestine short; peritoneum dusky; dorsal rays 7 to 9; anal 6 

 or 7; scales 60 to 70; lateral line continuous. Size small, 3 to 5 inches. 

 Species few, 2 in Illinois. Active fishes, inhabiting mountain springs of the 

 east and west and the swifter and cooler brooks of the central United States. 



Key to the Species of RHINICHTHYS found in Illinois 



a. Snout long and prominent, projecting far beyond the inferior mouth, less than 



2% in head and more than twice length of eye in adults cataractae. 



aa. Snout moderate, projecting little beyond the^ mouth (which is subterminal), 



more than 2% in head, and not over 1% times length of eye in adults 



atronasus. 



RHINICHTHYS CATARACTS (Cuvier & Valenciennes) 



long-nosed dace 



Cuvier & Valenciennes, 1842, XVI, 315 (Gobio). 



G., VII, 176 (Ceratichthys) and 189 (Rhinichthys marmoratus and R. nasutus) ; 



J. & G., 207; M. V., 63; J. & E., I, 306; N., 45 (nasutus and maxillosus) ; J., 62; 



F., 75 (atronasus, part). 



Distinguished from the next species by its longer snout, longer and 

 much projecting upper jaw J more elongate body, and less coarsely mottled 

 coloration. Length 2 x /i inches; depth 4.8 to 5.2 in length; caudal peduncle 

 as long as or longer than head, its depth 2.1 to 2.6 in its length. Coloration 



