272 CALIFORNIA ACADEMY OF SCIENCES. 



Head4-l-4J; depth 4J-5; D.I, 5; A. 10-11; V. 6; P. I, 6. 

 Numerous specimens, .07-. 16m. Rio Parahyba; Rio 

 Janeiro; Macacos. 



XLVIII. TRACHYCORYSTES. 



Tr achy cor ystes Bleeker, Nederl. Tijdschr. Dierkunde, 

 i, 88, 1863 (typus=tr achy cor ystes). 



Parauchenipterus Bleeker, 1. c. (galeatus). 



Type: Trachycorystes typus Bleeker. 



Caudal obliquely truncate or slightly emarginate; pos- 

 terior portion of the anal convex. Lower jaw usually 

 projecting. Barbels six, those of the mandible disposed 

 in two pairs. Teeth villiform, none on the vomer or 

 palate. Eye small, lateral, covered with skin. Adipose 

 fin very short. Dorsal fin with a spine, and from 4 

 to 6 rays. Anterior rays of the anal in the <3 enlarged, 

 bearing the urogenital organ. Ventral fins free, with 

 from 6-10 rays. Pectoral spine strong, serrated on both 

 margins. Occipital process firmly joined to the dorsal 

 plate, the latter with or without a descending angle be- 

 hind. 



Habitat: Rio Janerio to Rio Magdalena and Peru. 



As here understood, this genus contains various ele- 

 ments which it may become necessary to separate gen- 

 erically; on account of the scarcity of our material we 

 have not thought it best to do so at present. 



ANALYSIS OF THE SPECIES OF TR.ACHYCORYSTES. 



a. Head covered with thick, smooth skin. Eye 7 in head; lower jaw pro- 

 jecting; head depressed; fontanel surrounded by bone; snout short, 

 strongly rounded in front. Maxillary barbels longer than head; pec- 

 toral spine 1-J, dorsal spine 1^, width of head 1 in length of head; pec- 

 toral spine more strongly toothed on inner than on outer margin, 

 strongly depressed, stronger than dorsal spine which is smooth on outer 

 margin, with weak teeth on inner; humeral process pointed, granular. 

 Pectoral pore wanting. Caudal obliquely rounded, upper lobe a little 

 longer. Lat. 1. nearly straight. Color reddish violet; blackish mar- 

 blings on top of head ,nd elongate spots on body; fins with dark spots 



