SILURID.E. XXIV. 39 



35. TACHYSURUS Lacepede. (Galeiclithys and Arius Cuv. 

 & Val.) (ra^vy, swift ; ovpa, tail.) 



a. Teeth all pointed; top of head with a born' occipital shield which is not 

 covered by skin ; bands of palatine teeth without backward prolongation 

 on the median line; vomerine bands of teeth not confluent; ante-dorsal 

 shield small, crescent-shaped; eyes well above angle of month; species 

 with blue lustre in life. (Ariopsis Gill.) 



49. T. felis (L.). SEA CAT-FISH. Interorbital area flattish 

 and smooth, without ridges or granulations ; fins not low, the 

 spines more than half length of head ; vomerine teeth in a small 

 patch ; palatine teeth in a larger one, on each side, the four 

 patches separate ; fontanelle prolonged backward as a narrow 

 groove ; occipital process long, about ^ head, convex at tip, with 

 a median keel ; gill membranes not meeting at an angle ; maxillary 

 barbel nearly as long as head. L. 24. N. Y. to Mexico ; common 

 S. (Lat., cat.) 



36. ICTALURUS Rafinesque. (lx@vs, fish ; aiXovpos, cat.) 

 a. Anal fin very long ; its rays 32 to 35 ; its base nearly of body. 



50. I. furcatus (Cuv. &Val.). CHUCKLE-HEADED CAT. Silvery, 

 nearly plain ; eye small, wholly before middle of head ; head 4^ ; 

 depth 5. Miss, valley, not uncommon. (Lat., forked.) 



aa. 'Anal fin moderate; its rays 24 to 30; its base 3 to 4 in body. 



51. I. punctatus (Rafinesque). CHANNEL CAT. WH^TE CAT. 

 SILVER CAT. Olivaceous, rarely blackish, the sides silvery, al- 

 most always with small round dark olive spots ; eye large, not 

 wholly in front of middle of head ; mouth small ; barbels long ; 

 spines strong, serrate ; head 4 ; depth 5. L. 3 feet. Montana to 

 Vt., Ga., and Mexico, very abundant in flowing streams. A hand- 

 some fish, the best in the family as food. (Lat., spotted.) 



37. AMEIURUS Rafinesque. (a privative; ptiovpos, curtailed, 

 the tail not notched.) 



a. Caudal fin forked (species approaching Ictalurus). 



b. Anal rays 25 to 35; humeral process very short and blunt; usually 

 covered by skin, about length of pectoral spine. 



52. A. nigricans (Le Sueur). GREAT CAT-FISH. MISSISSIPPI 

 CAT. FLANNEL-MOUTHED CAT. Slaty bluish, growing darker 

 with age ; body stouter than in the Channel Cat, the head broader, 

 lower, and more depressed, the mouth wider, the caudal less forked, 

 the skin thicker, hiding the bones of the head ; head depressed 

 above ; supraoccipital above almost reaching second interspinal, 

 the bony bridge broken for a short distance only ; anal about as 

 long as head ; head 4 in length ; depth 5 ; D. I. 5 or 6 ; A. 25 to 



