22 Field Columbian Museum — Zoology, Vol. V. 



ing from internasal space to scarcely beyond the posterior margin of 

 the eyes; opercle with fine radiating striae; humeral spine extending 

 for about the first third of its length of the pectoral fin, covered with 

 a thin membrane ; origin of dorsal fin nearly midway between the 

 tip of the snout and origin of anal, its margin rounded; origin of 

 adipose fin near dorsal and extending to tips of depressed rays of 

 anal; origin of anal a little nearer base of the caudal than the dorsal; 

 caudal fin deeply emarginate, its lobes pointed; pectoral fin small, 

 reaching a little over half-way to the base of ventrals, its com- 

 pressed spine about two-thirds its length; ventrals inserted below 

 the posterior base of the dorsal fin, reaching about yi of its distance 

 to the anal. 



Color uniform dull russet brown; the upper half a little darker 

 than the lower; a pale shade on dorsal. Length 6yi inches. 



The above description was taken by Mr. Henry Fowler from the 

 type which is in the Museum of the Acad. Nat. Sci. Philadelphia. 

 This species is known only from this and one other specimen, n 

 inches in length, collected by the writer at Motzorongo. 



Rhamdia wagneri (Gunther). 



Pimelodus wagneri Gunther, Fishes Cent. Amer., 474, 1869; Atlantic and 

 Pacific Rivers of Panama. 



Rhamdia wagneri Jordan & Evennann, Bull. 47, U. S. Nat. Mus., 1896, 150: 

 Everniann & Goldsborough, Bull. U. S. Fish Comm., 1902, 146; Teapa 

 and Frontera, Tabasco. 



Southern Mexico to Panama. 



Head 4 to 4^2 ; depth 5 to 5 ' _> ; D. 1, 6; A. 9 or 10. Body elongate, tapering 

 backward from head and much' compressed posteriorly; head broad and flat, 

 slightly longer than wide, covered with soft, smooth skin ; interorbital width 2% 

 in head; eye small, high up on the head, its diameter 7^ to 8 in head; mouth 

 moderate, jaws equal; teeth in broad cardiform bands on each jaw';' maxillary 

 barbel reaching adipose fin; mental barbel reaching beyond base of pectoral; 

 occipital process narrow, reaching about half-way to dorsal spine ; base of adipose 

 fin 25^ to 3 in body, reaching slightly farther than anal; fontanelle not continued 

 beyond the eye. 



Color brown, lighter below; many dots over the body; a dark lateral band; 

 base of dorsal pale. Length probably about 18 inches. Specimens described 

 are from Teapa and Frontera. 



This species was taken at Teapa and Frontera, Tabasco, by Mr. E. W. 

 Nelson. So far this is the most northern record we have of it. The largest 

 specimen collected by Mr. Nelson is 14X inches in length. 



19. Rhamdia hypselura (Gunther). 



Pimelodus hypselurus Gunther, Cat., v, 126, 1864; Mexico. 

 Rhamdia hypselura Jordan & Everniann, Bull. 47, U. S. Nat. Mus., 



1895. J 52. 



Head 5; depth 6; D. 1, 6; A. 13. Body elongate, apparently quite 



slender; lower jaw the shorter, the band of teeth in the upper jaw 



about five times as broad as long; eyes near middle of head, their 



diameter being % width of interorbital space ; head covered with soft 



