2()4 CALIFORNIA ACADEMY OF SCIENCES. 



XLV. TRACHELYOPTERUS. 



Trachelyopterus Cuv. & Val. Hist. Nat. Poiss. xv, 2'20, 

 pi. 438, 1840 (coriaceuH). 



Type: Trachelyopterus coriaceus Cuv. & Val. 



Adipose fin none. Ventral fins of six rays, anal of 

 moderate length. Barbels 6, those on the chin disposed 

 in two series. Bones of the head exposed/ granular. 

 Fontaiiel oval. Dorsal plate coalesced with the occipital 

 process. Humeral process present. Gill-membranes con- 

 fluent with the skin of the isthmus. Teeth villiform, 

 none on the vomer. 



204, Trachelyopterus coriaceus. 



Trachelyopterus coriaceus Ctiv. & Val. 1. c. (Cayenne); Giinther, 

 Cat. Fish. Brit. Mus. v, 198, 1864 (copied); Eigenm. & Eigeimi. 

 Proc. Cal. Acad. 2d Ser. i, 157, 1888 (Obidos; Porto do Moz). 



Habitat: Amazon; Cayenne. 



Body short and compressed. Head short, its width 

 and depth equal to its length; profile steep, snout trun- 

 cate, the lower jaw entering the profile; bones of the 

 head and the humeral process finely granular. 



Eye small, round, 6 in the head, 3J in the interorbital. 



Maxillary barbels reaching about to tip of humeral 

 process; mental barbels about half as long as the head, 

 the postmentals somewhat longer than the maxillary bar- 

 bels. 



Teeth villiform, in narrow bands. 



Distance of dorsal spine from snout 3-3J in the length ; 

 dorsal spine weak, terete, its anterior margin smooth, 

 its posterior with short teeth; its height little less than 

 the head. 



Caudal obliquely rounded. Ventrals reaching the 

 anal. 



Pectoral spine smooth on its outer margin, short teeth 

 on its inner margin, 1 in the head. Humeral process 

 extending a little past the middle of the pectoral spine. 



