336 Field Museum of Natural History — Zoology, Vol. VII. 



branes broadly connected with the isthmus; ventrals with i con- 

 cealed spine and 4 soft rays; no slit behind fourth gill. 



a. Preopercular spine short, its length less than % diameter of 

 eye; caudal peduncle slender, its depth 1.5 to 2 in its length. 



ictalops, 336 

 aa. Preopercular spine long, its length more than % diameter of 

 eye; caudal peduncle slender, its length 3.3 in its length. 



ricei, 336 



Cottus ictalops (Rafinesque). Common Sculpin; Miller's Thumb. 



Head 3.0 to 3.5; depth 3.7 to 4.3; D. viii to ix, 16 to 18; A. 13 

 to 15. 



Body fusiform; head broad, convex above; interorbital space 

 3.8 to 5.5 in head; mouth wide, lips thick; maxillary reaching to 

 middle of the orbit; snout 2.8 to 3.4 in head; preopercular spine 

 short, its length less than half diameter of the eye; spinous dorsal 



Fig. 77. Common Sculpin; Miller's Thumb. 



Cottus ictalops (Raf.). (From Forbes and Richardson.) 



about 3/8 height of soft dorsal; body without scales, a few prickles 

 present behind pectorals; lateral line continuous or interrupted 

 posteriorly. 



Color olivaceous, more or less barred or blotched with darker 

 fins mostly barred or mottled. 



Length 3 to 7 inches. 



This, fish inhabits clear streams from North Dakota to North Car- 

 olina and Oklahoma, 



Lockport, Illinois; Lake Michigan, Chicago, Illinois. 



Cottus rlcel (Nelson.) 



Head 3.2 to 3.6; depth 5.3 to 6.2; D. vii, 16; A. 13. 



Body slender; head depressed, as wide as long; interorbital space 

 narrow, 8.2 in head; mouth narrow, the maxillary scarcely reaching 



