00 FISHES OF ILLINOIS 



in rapid water under stones. It feeds, so far as our observations go, 

 almost wholly upon aquatic larva?, mainly those of day-flies, more 

 than half of the food of the specimens examined consisting of a 

 single form (Ccenis) abundant under stones. 



A few aquatic larvae of a gnat (Chironomus), and some other 

 insect remains, with an insignificant ratio of small bivalve mollusks, 

 were the other elements of its food. 



It ascends the swifter brooks in spring, no doubt for spawning, 

 although its habits of reproduction are not known. It is sometimes 

 used for food, but has virtually no economic value. 



Genus MOXOSTOMA Rafinesquk 



(red-horse) 



Body more or less elongate, usually more or less compressed; mouth 

 inferior; lips with transverse plicae, the folds rarely so broken up as to 

 form papillae; posterior fontanelle always well open; supraorbital bone 

 wanting; suborbitals very narrow; pharyngeal bones weak, the teeth 

 rather coarser than in Erimyzon and Catostomus; vertebrae {aureolum, 

 breviceps) 39 to 41 ; ribs 15 to 17; dorsal rays 1 1 to 17, usually about 13; 

 scales large, usually about 44 in the median lateral series; lateral line 

 well developed; air-bladder with 3 chambers. Males in spring with lower 

 fins reddened (whence the common name), and with anal rays swollen 

 and tuberculate. 



United States, east of the Rocky Mountains; species numerous; 

 3 species found in Illinois. 



The gill-rakers of the red-horse are largely modified into trans- 

 verse leaf-like plates with notched edges projecting in triangular 

 outline only a little beyond the margin of the thick, strong arch. 

 Those of tlie anterior gill are more elongate, but stout and triangu- 

 lar, and about three fourths as long as the gill-filaments, the whole 

 branchial apparatus being thus coarse and strong, 1 utter adapted 

 to hold hard and somewhat bulky objects than to strain from the 

 water small and delicate ones. The pharyngeal jaws are moderately 

 heavy, with strong teeth, and the intestine is small and about one 

 and a fourth times the length of the head and body. Quite in cor- 

 respondence with these features of the feeding apparatus, the main 

 food of tlie red-horse consists of water-snails of various species, and 

 small bivalve mollusks belonging to the genus Spharium. About a 

 third of the food of specimens examined by us consisted of insects, 

 practically all aquatic larvae. The vegetable mailer present in the 

 food of specimens taken from the Illinois River at Peoria was mainly 



