CATOSTOMUS — FINE-SCALED SUCKERS 85 



CATOSTOMUS COMMERSONII (Lacepede) 



(common sucker; fine-scaled sucker) 



Lacepede, 1803, Hist. Nat. Poiss., V, 502 (Cyprinus). 



G.. VII. 15 (teres); J. & G., 129; M. V.. 46 (teres); J. & E.. I, 178; N., 4S (teres); 

 J., 64; F., 81 (teres); F F., II. 7, 444 (teres); L., 12. 



Body elongate, subterete, rather heavy forward, depth 4.3 to 5.3 in 

 length, usually 4.5 to 5. Length 18 inches. Color olivaceous on back 

 and sides, with more or less golden luster; belly whitish; vertical fins 

 with some dusky on rays, membranes paler, those of ventrals and pec- 

 torals orange, becoming deeper in spring males, which also have a faint 

 rosy latera. band. Young brownish with blackish blotches and mottlings 

 which are more or less confluent, sometimes forming an indistinct lateral 

 band. He .d rather stout, subconical, flattish above, its length 4 to 4.8, 

 width 5. 5 to 7, depth 5.5 to 6.6 in body; interorbital space nearly flat, 

 2.1 to 2.6 in head; snout blunt, decurved, squarish at tip; mouth 

 inferior, rather large, the lips strongly papillose, the upper rather thick, 

 with 3 or 4 rows of papillae; eye moderate, 4.5 to 6.2 in head, more than 

 5 in adults. Dorsal tin with 11 to 13, usuallv 12, rays, its height scarcely, 

 if at all, exceeding the length of the fin's base. Scales 10-11, 63-80, 

 9-11, crowded anteriorly and below; lateral line complete in adults, 

 pores wanting on some scales in young. 



The fine-scaled sucker occurs in streams and ponds from the 

 Great Lakes to New Brunswick and Laborador, in the Hudson 

 River, on the Atlantic slope from New Jersey to South Carolina, and 

 northward to Great Bear Lake and Hudson's Bay. It is abundant 

 throughout the central part of the eastern United States from 

 Massachusetts to Kansas, and is common in the northern third of 

 Illinois, especially in the smaller rivers and larger creeks. It occurs 

 but rarely in the Illinois River as far south as Peoria, and has not 

 been taken by us south of Alton except in the streams of extreme 

 southern Illinois below the Illinoisan glaciation. It is with us 

 essentially a species of creeks and small rivers, nearly four times as 

 common, according to our data, in the former as in the latter. It 

 has been taken but four times in our 293 collections from rivers of 

 the larger size, and but twice from 591 collections made from lakes, 

 ponds, and sloughs. It is common, however, in Lake Michigan. 

 Our collection data show that it is much more likely to be abundant 

 on bottoms with more or less rock and sand than on a completely 

 muddy bottom, and that it has also a decided preference for clear, 

 swift waters. The species reaches a length i if 22 inches and a weight 

 i if 5 lb. 



The food of this sucker has not been carefully studied, but the 

 strong, thick pharyngeal jaws, nearly twice as wade as high, and the 



