322 CALIFORNIA ACADEMY OF SCIENCES. 



Ventrals short, with the basal half of their inner mag- 

 gins attached to the belly. 



First pectoral ray lengthened, reaching past the base 

 of the ventrals, a little shorter than the head, its tip 

 broken, probably longer than the head. 



Dorsal surface grayish brown, becoming gray on sides, 

 lighter below. 



Head 3|; depth 4; D. 7; A. 21; V. 6; P. 10. 



One specimen, ? , length .23 m. Gurupa. Louis 

 Agassiz. 



252. Cetopsis gobioides. 



Cetopsis gobioides Kuer, SB. Ak. Wieu, xxvi, 407, 1857, pi. vi, fig, 16 

 (Irisauga); Gtinther, Cat. Fish. Brit. Mus. v, 199, 1864 (copied). 

 Silurus pygmcens Natterer in Kner. 1. c. 

 Habitat: Irisauga. 



This species is known only from the types. 



253. Cetopsis occidentalis. 



Cetopsis occidentalis Steindachner, Fisch-fauna des Cauca and Fltisse 

 bei Guayaquil, 47, plate viii, fig. 2-2a, 1880 (Rivers near Guaya- 

 quil). 



Habitat: Giiayaquil. 



This species is known only from the types. 



254. Cetopsis ventralis. 



Cetopsis ventralis Gill, Pi'oc. Acad. Nat. Sci. Pliilad. 1870, 95 (Upper 



Amazon). 

 Habitat: Upper Amazon. 



LVIII. Nematogenys. 



Nematogenys Girard, Proc. Acad. Nat. Sci. Phila. 1854, 

 198 (i neviids). 



Type: Trichomycterus inermis Guichenot. 



Dorsal fin placed over the ventrals, without a spine. 

 Fontanel extending to base of occipital process, interrupted 

 above the posterior margin of orbit. Opercle and pre- 

 opercle unarmed. A single barbel on each maxillary 

 and one pair of mental barbels. 



Habitat: Central Chile. 



