38 TELEOSTEI: NEMATOGNATHI. — XI. 



Family XXIV. SILURID^. (The Cat-fishes.) 



Body more or less elongate, naked or with bony plates ; margin 

 of upper jaw formed by premaxillaries only, the rudimentary 

 maxiUaries forming the base of a long barbel ; teeth in villiform 

 bands. Dorsal fin usually present, short, above or before ventrals ; 

 usually an adipose fin behind dorsal. First ray of dorsal and pec- 

 torals usually developed as a stout spine. Lower pharyngeals 

 separate. Air-bladder present, large. A vast family of more 

 than 100 genera and 900 species, mostly of the rivers and swamps 

 of warm regions, especially of South America and Africa. A few 

 species are marine. Many of them are excellent as food, and aU 

 are very tenacious of life. 



a. Dorsal short, placed before ventrals ; adipose fin present; gill membranes 

 more or less free from isthmus ; body naked. 

 b. Anterior and posterior nostrils close together, neither with a barbel, the 

 posterior with a valve; palatines with teeth; caudal forked. Marine 

 species. (Tachysurincs.) 



c. Lower jaw with 2 barbels; maxillary barbel band-like; dorsal and 



pectoral spines ending in striated filaments. . Ailueichthys, 34. 

 cc. Lower jaw with 4 barbels ; spines not filamentous. Tachtsukus, 35. 

 bb. Anterior and posterior nostrils well separated, the posterior with a 

 barbel; barbels 8; teeth in jaws only. (Ictalurinoe.) 



d. Adipose fin with its posterior margin free. 



e. Premaxillary band of teeth, without backward processes. 

 f. Supraoccipital bone prolonged backward so that its emarginate 

 apex fits closely around the anterior point of the second inter- 

 spinal, thus forming a continuous bony bridge extending from 

 the head to the dorsal spine. (Silvery species ; C. deeply 



forked.) Ictaltjkus, 36. 



ff. Supraoccipital bone not reaching the second interspinal, the bony 

 bridge more or leas interrupted. 



g. Eyes normal Ameiurus, 37. 



gg. Eyes concealed by the skin Geonias, 38. 



ee. Premaxillary band of teeth, with a lateral backward process on 



each side ; lower jaw prominent Leptops, 39. 



dd. Adipose fin keel-like, adnate to the back, more or less joined to 

 caudal fin; a (venom) pore in axil of pectoral. . N"otuecs, 40. 



34. AILURICHTHYS Baird & Girard. (atKovpos, cat; 

 IxOvs, fish.) 



48. A. marinus (Mitchill). Gaff-Top.sail. Sea Cat. Dusky 

 bluish. Head short and broad. Maxillary barbels reaching end 

 of P. spine ; P. filament reaching vent, D. filament to adipose fin ; 

 upper lobe of C. longer ; palatine teeth in a nearly continuous 

 band. Head 4^. D. I. 7. A. 23 L. 30 in. N. Y. to Texas, 

 common S., not entering streams. 



