FAMILY III. SILURIDJE. 13 



KEY TO THE SPECIES OF AMIURUS. 



a. Caudal fin lunate or forked. PAGE 



b. Base of anal fin longer than head, its rays 24 

 or more; upper jaw the longer. 



c. Head very broad, not narrowed forward; 

 dorsal spine 2^ in head; pectoral spine 2?, 



its inner margin rough, but without teeth .australis 13 



cc. Head less broad, and narrowed forward; 

 dorsal spine long, its length if in head; 

 pectoral spine i^ in head, its hinder margin 



with 7 to 9 retrorse teeth lupus 14 



bb. Base of anal fin equal to or shorter than the 

 head; anal rays about 20. 



d. Dorsal spine long, 134 to if in head; pec- 

 toral spine weakly serrate on inner margin. 



e. Pectoral spine strong, its length 2 in head; 

 caudal fin deeply forked, its inner rays less 



' than half its outer dugesi 14 



ee. Pectoral spine moderate, its length 2f in 

 head; caudal fin moderately forked, its 



inner rays i^ in the outer mexicanus 15 



dd. Dorsal spine short, 2% in head; pectoral 

 spine short and strong and strongly serrate 



on its inner margin, its length 2| in head pricei 15 



aa. Caudal fin truncate, or very slightly lunate; 



anal rays 24 to 27 natalis 16 



Subgenus Haustor Jordan & Evcrmann. 



8. Amiurus australis sp. nov. 



Type, No. 4474, F. C. M., 17.7 inches in length; Forlon, Tamauli- 

 pas. 



Rio Panuco to the Rio Blanco in Southern Vera Cruz. (Forlon; 

 Rio Blanco.) 



Head 3^; depth 5^; D. i, 6; A. 26. Body elongate, head 

 broad and much depressed, its greatest width i^ in its length; 

 interorbital 2^; eye father small, 6^ in head; upper jaw consid- 

 erably the longer; teeth on jaws in bands, and without backward 

 projections; maxillary barbels long, their tips reaching middle of 

 pectoral fin; dorsal spine 2| in head; pectoral spine rather strong, 

 2^ in head, its inner margin rough, but without teeth; anal fin long, 

 its base slightly longer than head; caudal fin forked, but less so than 

 in species of Ickthy&lurus; least depth of caudal peduncle 3 in head. 



