CATOSTOMUS — FIN K-si AI.l I> slVKKKS 85 



CATOSTOMUS COMMERSONII (Lacepede) 



common sucker; fine-scaled sucker 

 (Map XVIII) 



Lac£pede, 1S03, Hist. Nat. Poiss., V. 502 (Cyprinus). 



G., VII, 15 (teres); J. & G., 129; M. V., 46 (teres); J. & E., I, 178; N., 48 (teres); 

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



Body elongate, subteretc, 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 pectorals orange, 

 becoming deeper in spring males, which also have a faint rosy lateral band. 

 Young brownish with blackish blotches and mottlings which are more or 

 less confluent, sometimes forming an indistinct lateral band. Head rather 

 stout, subcorneal, flatfish 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 papilla?; eye moderate, 

 4.5 to 6.2 in head, more than 5 in adults. Dorsal fin with 11 to 13, usually 

 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 fin-scaled sucker occurs in streams and ponds from the 

 Great Lakes to New Brunswick and Labrador, 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 giaciation. 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 of 22 inches and a weight of 5 lb. 



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

 the strong, thick pharyngeal jaws, nearly twice as wide as high, 



