SCHILBEODES 197 



SCHILBEODES GYRINUS (Mitchill) 

 (tadpole cat) 



Mitchill, 1818, Amer. Month. Mag., 322 (Silurus). 



J. & G., 98 (Noturus); M. V., 42 (Noturus) ; }. & E., I, 146; J-. 68 (Noturus sialis); 

 F., 84 (Noturus); F. F. II. 7, 462 (Noturus); L., 10. 



Form robust, the body shorter and deeper than in other species; 

 depth 3 . 8 to 4 . 4 in length. Length of adults 3 to 5 inches. Color oliva- 

 ceous to almost blackish, top of head darker; translucence of skin giving 

 rise to a marked light purplish or flesh color on sides in strong light; a 

 dark median lateral streak on side extending to base of caudal, a similar 

 fainter one near belly, and two higher up on side, the upper one extending 

 along base of adipose fin ; belly, breast, and chin yellowish ; pupil dull dark 

 blue, iris bluish, tinged with gold or coppery; fins plain, all except ven- 

 trals and pectorals a rather dusky olive. Head large and fleshy, broad 

 forward, short and flat, the contour from snout to dorsal steep and almost 

 straight ; length of head 3.2 to 3.9, width 3 . 6 to 4 . 9 in length of body ; 

 interorbital space 1.6 to 2.1 in head, eye 6.3 to 7.6; jaws about equal; 

 barbels barely reaching gill-opening. Dorsal fin placed well forward, its 

 distance 2.5 to 2.9 in length; the spine rather long, more than h the 

 height of fin, 2 . 4 to 2 . 9 in head. Caudal rather long, broadened mesially 

 and tapering slightly to its truncate end. Anal short, its rays 13 to 15. 

 Pectoral spine strong, its length 1 . 9 to 2 . 4 in head, tapering evenly from 

 the base to the sharply pointed tip, its upper surface strongly ridged and 

 grooved diagonally, not flattened as in 5. nocturnus; the anterior edge 

 entirelv smooth or with 2 or 3 obscure points near tip; posterior edge 

 smooth; humeral process moderate, its length less than 4 in pectoral 

 spine. Lateral line developed anteriorly, much interrupted or alto- 

 gether wanting on posterior half of body. 



This fish, although distributed throughout the state, is most 

 abundant in our collections to the southward and eastward in the 

 branches of the Kaskaskia and the Wabash. The species enters 

 with special freedom the lower Illinoisan glaciation, avoided by 

 Noturus flavits. We have found it about equally common in large 

 rivers, creeks, and lowdand and upland lakes, but for some unex- 

 plained reason only three of our 193 collections have come from the 

 smaller rivers. It is more abundant, relatively to the number of 

 collections made, in still and muddy waters than in those with a 

 rapid current and a clean bottom, our frequency coefficients for the 

 first and second of these situations being 1 .47 and 1 .45 respectively. 

 According to Professor Hay, it is accustomed to hide under stones 

 and logs. 



Generally speaking, it is a species of wide range, from the Hudson 

 River on the east through the Great Lakes to the Dakotas and 

 Montana, and from this line southward to the Florida peninsula 



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