CARPIODES — CARP-SUCKERS / 3 



is closed, and the longest of the anterior series are a little longer 

 than the corresponding filaments. 



Nineteen specimens, representing 13 localities from extreme 

 northern to extreme southern Illinois, and various dates from April 

 to October, indicate that our native carp -differ from their near 

 allies, the buffalo -fishes, in the smaller amount of vegetation eaten, 

 in the greater quantity of mud mingled with the food, and in a de- 

 ficiency of the larger insect larvae. The vegetable food of these 

 specimens was only 8 per cent., mostly the small duckweed, Wolffia. 

 Mollusks made about a fourth of the food, all the thin-shelled bivalve 

 Sphcerium. Insects averaged about a third, the greater part larvae 

 of Chironomus. Entomostraca made nearly a fourth, and included 

 a considerable list and variety of our more abundant species. 



Key to the Species of CARPIODES found in Illinois 



a. Snout short, 3| to \\ in head; nostrils well forward, the distance from an- 



terior nostril to end of snout considerably less than diameter of eye; tip of 

 lower jaw little in advance of nostrils. 



b. Body robust, subfusiform, depth 2$ to 3 in length; snout obtusely pointed; 



eye moderate, 4J to 5 in head; anterior rays of dorsal scarcely elevated, 



osseous at base; large species, reaching over ; 5 rb in weight carpio. 



bb. Body thin and compressed, the back much elevated in adults, depth 2\ to 



2f in length; snout very blunt, squarish at tip; eye large, 3J to 4| in head; 



anterior rays of dorsal much lengthened, sometimes equaling length of 



base of fin; small species, not over 12 inches in length difformis. 



aa. Snout longer, 3 to 3 \ in head; nostrils situated well back, the distance from 



anterior nostril to end of snout usually greater than diameter of eye ; tip 



of lower jaw far in advance of nostrils. 



c. Body robust, subfusiform, depth 2f to 3£ in lepgth; anterior rays of dorsal 



scarcely elevated , about \ length of base of fin ; halves of lower tip meeting 



at a wide angle; large species, reaching a weight of 5 lb thompsoni. 



cc. Body compressed, the back more or less arched, depth 2\ to 3 in length; 

 anterior rays of dorsal much elevated, nearly or more than equaling 

 length of base of fin ; halves of lower lip meeting at a sharp angle ; species 

 of small size, not exceeding 12 inches , velifer. 



