SCHILBEODES 197 



SCHILBEODES GYRINUS (MITCHILL) 



TADPOLE CAT 



(MAP LVIII) 



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



J. & G., 98 (Noturus); M. V., 42 (Noturus); J. & 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 olivaceous 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 ventrals 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 ^ 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 S. nocturnus; the 

 anterior edge entirely 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 altogether 

 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 flavus. We have found it about equally 

 common in large rivers, creeks, and lowland and upland lakes, 

 but for some unexplained reason only three of our 193 collec- 

 tions 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 Pro- 

 fessor 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 



