i8 Field Columbian Museum — Zoology, Vol. V. 



Color bluish slate above, light silvery below; a few small dark 

 spots on head and sides; fins dusky. Length 3 feet or more. 



This is the only member of the catfish family yet known from 

 the basin of the Rio Balsas, where it lives in the clear deep water of 

 the main stream and its larger tributaries. It is an excellent food fish. 



7. Leptops Rafinesque. 

 Mud-cats. 



Leptops Rafinesque, Ichth. Ohiensis, 64, 1820. (Type, Silurus vis- 

 cosus Rafinesque =Silurus olivaris Rafinesque.) 



Body elongate, slender, much depressed anteriorly; head large, 

 very wide and depressed; skin very thick, entirely concealing the 

 skull ; supraoccipital bone entirely free from the head of second inter- 

 spinal; eyes small; mouth very large, the lower jaw always project- 

 ing beyond the upper; teeth in broad villiform bands on premaxil- 

 laries and dentaries; band on the upper jaw convex anteriorly, and 

 at insertion of the maxillaries, proceeding backward as an elongated 

 triangular extension; premaxillary band of teeth slightly divided at 

 the symphysis ; lower band of teeth attenuated at the corners of the 

 mouth; branchiostigals 12; adipose fin large, its posterior margin free; 

 dorsal and pectoral each with a spine-like ray; anal fin small; caudal 

 oblong and truncate. 



15. Leptops olivaris (Rafinesque). Mud-cat; Bagre; Besugo. 

 Silurus olivaris Rafinesque, Amer. Monthly Mag., 1818, 355; 



Ohio River. 

 Amiurus punctulatus Gunther, Cat., v, 101, 1864. 

 Leptops olivaris Woolman, Bull. U.S. Fish Comm., 1894, 56; Rio 

 Grande, El Paso, Texas: Jordan & Evermann, Bull. 47, U. 

 S. Nat. Mus., 1895, 143: Meek, Field Col. Mus. Pub. 65, 1902, 

 74; Santa Rosalia. 

 Northeastern Mexico, north of the Rio Panuco, and streams of 

 the southern United States and the Mississippi Valley. 



Head sH'> depth 6; D. 1, 7; A. 12 to 15. Body slender, depressed 

 forward, the head extremely fiat; lower jaw projecting; snout 3^ in 

 head; barbels short, maxillary barbels reaching slightly beyond base 

 of pectoral; eye small, 7 in head; dorsal spine very weak, 2 in height 

 of the fin ; anal fin short, its base 6 1 4 in the body ; humeral process short ; 

 pectoral spine strong, serrate on both edges, its length 3 in head; 

 caudal fin slightly emarginate. 



Color yellowish, much mottled with brown and greenish, whitish 

 below. Length 3 to 4 feet. 



