138 FISHES OF ILLINOIS 



about % to ventrals, 1.2 to 1.4 in head; ventrals reaching vent or front of 

 anal. Scales 5, 32-36, 4; 12 or 14 before dorsal; lateral hne complete, general- 

 ly noticeably decurved on anterior half of body. 



This abundant but rather insignificant and indefinite species 

 belongs to the group which apparently avoid the streams of the 

 southern Illinoisan giaciation. Although distributed through- 

 out the state from the Ohio and Saline rivers on the south to the 

 extreme northern boundary, and represented in our records by 

 128 collection localities, but five of these are within that area, 

 and these are on its northern borders where its peculiarities are 

 least pronounced. It is consistent with this limitation to its 

 distribution in this state that it should show a decided preference, 

 according to our collection records, for clean swift waters over 

 mudd}^ and stagnant ones. Its frequency coefficient for waters 

 over a bottom of rock or sand is 2.00, and the corresponding 

 frequency ratio for a swift current is 1.18. It is essentially a 

 species of small rivers and creeks, our frequencies for these two 

 classes of streams being 2.65 and 2.23 respectively, while that 

 for the larger rivers is only .41 and that for lakes and ponds but 

 .17. In general distribution it is limited to a region extending 

 from the Great Lake basin. Lake Champlain, and the streams 

 of the St. Lawrence system, by way of the Missouri River to 

 Wyoming, northward to the Lake of the Woods and the Red 

 River of the North, and southward through the Ohio and the 

 Mississippi basins to the San Antonio River in Texas. 



From the little that is known of its feeding habits, its food 

 is no more peculiar than its general appearance, consisting of a 

 mixture of aquatic insects, crustaceans, and chance vegetation. 



NOTROPIS PHENACOBIUS Fokbes 



Forbes, 1885, Bull. 111. State Lab. Nat. Hist., IL 2, 137. 



This fish unites with a strong general resemblance to Phenacohius the 

 characters of Notwpis. The body of the adult is short and deep, the head 



square, the nose long, and the eye unusually large. 

 Length 2)4. inches; depth 3.5 to 4; caudal peduncle 4 

 to 4.75. Color in alcohol indefinite; sides somewhat 

 silvery, scales along and above the lateral line slightly 

 specked with black. The head is quadrate in trans- 

 verse section, flat above, 3.75 to 4; nose decurved, 3.4 

 Fig 3.3 to 3.5; interorbital space 2.9 to 3.1. The mouth is 



inferior, horizontal, rather small, lips fleshy, not lobed, 

 lower jaw much the shorter, 2.75 to 3.1 in head, upper lip opposite the lower 

 margin of the pupil, upper jaw to posterior margin of nostrils, 3.33 to 3.9 



