206 CALIFORNIA ACADEMY OF SCIENCES. 



ing it. Postorbital portion of the head striated and 

 granulated. Skin on the sides of the head and snout 

 reticulated. 



Habitat: Northern Brazil and northward. 



151. Hemisorubim platyrhynchos. 



Platystoma pldtiirhii nchos Guv. k Val., Hist. Nat. Poiss. xv, 27, 1840 



(no locality); Castelnaii, Aiiim. Noi;v. Rares de I'Amer. du Slid, 



40, 1865 (Amazon); Kner, SB. Ak. Wien, xxvi, 1857, .398 (Barra 



do Rio Negro.) 

 Hemisorubim platyrhynchos Bleeker, Nederl. Tijdschr. Dierk. 1863, 



97 (name only); Eigenm. & Eigeum. Pi'oc. Cal. Acad. 2d Ser. 



i, 138, 1888 (Manacapuru; Rio Negro; Moutalegre; Rio Puty; 



Lago Alexo; Obidos; Coary; Tabatiuga; Hj'avarj^; Tonantius; 



Sao Paolo.) 

 Hemisorubim platyrhynchus Gtiuther, Cat. Fish. Brit Miis. v, 109, 



1864 (copied); Peters, MB. Ak. Berl. 470, 1877 (Calabozo); 



Cope, Proc. Am. Pliilos. Soc. xvii, 674, 1878 (Peruvian Amazon); 



Vaillant, Bull. Soc. Philom. Series 7, iv, 152, 1880 (Calderon). 

 Habitat: Orinoco, Amazons, Paranahyba and their tributaries. 



This species agrees with Plafi/stomatichtJujs siitrio in 

 coloration, having large black spots scattered on the 

 sides and a black spot at base of caudal. 



Head depressed, rounded on occiput. 



Eye directed upward, 7 in head, 3 in snout, If in 

 interorbital. 



Lower jaw projecting and entering the profile. 



Maxillary barbels extending past dorsal; mental bar- 

 bels approximated, extending to below eyes; post- 

 mentals to pectorals. 



Teeth in the lower jaw in a nar- 

 row band. Vomerine and palatine 

 teeth close behind the maxillary 

 teeth; the vomerine teeth in a 

 single patch separate from the pal- 

 atine patches. 



Dorsal spine weak and slender, 

 2i- in head; its distance from snout greater than its dis- 

 tance from the posterior margin of the adipose fin; much 



