The Catfishes 



(Ameiurus dugesi) is known from various parts of the great 

 valley of the Rio Lerma in Mexico, a large stream which flows 

 through Lake Chapala into the Pacific Ocean; another (Istlarius 

 balsanus), is a very large catfish in the basin of the Rio Balsas, 

 described from Puente de Ixtla, in Morelos, Mexico ; and another 

 (Ameiurus pricei), from San Bernardino Creek in southern Arizona, 

 also tributary to the Pacific. 



No species of catfish is native to the fresh waters of the 

 Pacific Coast of the United States, though 2 species, Ameiurus 

 nebulosus and Ameiurus catus, have been introduced from the 

 East and have become very abundant in the Sacramento and San 

 Joaquin. 



a. Adipose fin with its posterior margin free. 



b. Premaxillary band of teeth truncate behind, not produced back- 



ward at the outer angles. 



c. Supraoccipital bone continued backward from the nape, its 



notched tip receiving the bone at base of dorsal spine, so 

 that a continuous bony bridge is formed under the skin 

 from snout to base of dorsal; tail forked ;.... Ictalurus, 16 



cc. Supraoccipital not reaching interspinal bones, the bony bridge 

 being more or less incomplete; Ameiurus, 23 



bb. Premaxillary band of teeth with a lateral backward extension 

 on each side ; Leptops, 3 \ 



aa. Adipose fin keel-like, adnate to the back and continuous with 

 the caudal fin ; Noturus, 33 



GENUS ICTALURUS RAFINESQUE 

 The Channel Cats 



Body elongate, slender, compressed posteriorly ; head slender 

 and conical; mouth small, terminal, the upper jaw the longer; 

 teeth subulate, in a short band in each jaw; dorsal fin high, with 

 one long spine and usually 6 rays ; adipose fin over posterior 

 portion of anal, which is long, with 25 to 30 rays ; ventral fins, 

 each with one simple and 7 branched rays; pectorals, each with 

 a stout spine, retrorse-serrate within, and about 9 rays; caudal 

 fin long, deeply forked, the lobes pointed, the upper the longer. 

 Colour, pale bluish, lead colour, or silvery. 



This genus is confined to the fresh waters of North America 

 and contains four known species, all except one (I. meridionalis, 



16 



