SOUTH AMERICAN NEMATOGNATHI. 339 



274. Eremophilus mutisii. 



Eremophilus mutisii Humboldt, 1. c. (Bogota); Valenciennes, Hum- 

 boldt, 1. c. ii, 340, 1835; Cuv. & Val. Hist. Nat. Poiss. xv, 500, 

 pi. 553, 1846 (Bogota); Gtuither, Cat. Pish. Brit. Miis. v, 275, 

 1864 (copied); Eigeum. & Eigenm. Proc. Cal. Acad. Sci. •2d Ser. 

 ii, 53, 1889. 



Trachijpoiaa marmoratum Giebel, 1. c. (loc. ?). 



Habitat: Tributaries of the Eio Magdaleua. 



Yellowish with reticulating brown lines and dots. 

 Head 6; Br. 8; D. 11; A. 9. (Valenciennes.) 



LXII. Tridens. 



Trideii'^ Eigenm, & Eigenm. Proc. Cal. Acad. 2d Ser. 

 i, 53, 1889 (melanops). 



Type : Tridens melanops E. & E. 



Ventrals small, nearer tip of snout than to base of 

 caudal. Anal long, inserted in front of the dorsal fin. 

 Head greatly depressed, the eye infringing on the upper 

 and lower surfaces of the head. A series of fine labial 

 teeth; stronger teeth in the jaws. Gill-membranes 

 united, forming a broad, free fold across the isthmus. 

 Opercle and preopercle armed. Maxillary barbels 2. 



275. Tridens melanops. 



Tridens melanops Eigenm. & Eigenm. 1. c. (Icja). 

 Types, No. 8137. Twenty-seven specimens, the largest .027 ni. 

 I(;a. James. 



Body compressed, extremely slender. Head broad, 

 the snout rounded; mouth broad, inferior. Opercle long 

 and slender, terminating in three spines, trident-shaped. 

 Preopercle with similar but smaller spines. Barbels min- 

 ute, scarcely evident. 



Distance of origin of dorsal fin from extremity of cau- 

 dal 3 ill the length; origin of anal fin from extremity of 

 caudal 2i in the length. Anal rays rapidly decreasing 

 in height backward, the last ray about over the last ray 

 of the dorsal. Caudal rounded, without accessory rays. 



