SOUTH AMERICAN NEMATOGNATHI. 461 



448. Hoplosternum melampterum, 



f'allichthys melampterun Cope, Proc. Acad. Nat. Sci. Philad. 1871, 



275, pi. xiv, fig. 4 (Ambyiacu Eiver). 

 Hoplosternum mdampterus Eigenm. & Eigenra. Proc. Cal. Acad. 2d 



Ser. i, 165, 1888 (name only). 

 Habitat: Ambyiacu River. 



XCVIII. DECAPOGON. 



Decapogon Eigenm. & Eigenm. Proc. Cal. Acad. 2d 

 Ser. i, 165, 1888. 



Type: Gailichthys adspersus Steindachner. 



449, Decapogon adspersum, 



Calliehthys adspersus Steiudachner, Ichthyol. Beitr. v, 87, pi. xi, 

 figs. 2-2b (Santarein to Tabatiuga; Xiugu, near Porto do Moz). 



Decapoyon adspersus Eigenm. & Eigenm. Proc. Cal. Acad. 2d Ser. i, 

 165, 1888 (Cudajas; Tabatinga; Porto do Moz). 



Habitat: Porto do Moz to Tabatinga. 



Body deepest at the dorsal spine, its width about 1| in 

 its depth, tapering backward to the slender, low caudal 

 peduncle. Profile from tip of snout straight and steep 

 to the occiput, thence curved to the dorsal spine; trans- 

 verse profile of the head everywhere gently arched; apex 

 of the nuchal plates angular. Fontanel ovate or elongate. 

 Suborbital bone narrow, its surface and the opercles 

 hispid. 



Inner rictal barbels longest, about reaching extremity 

 of pectoral spine; six short barbels on the lower lip, the 

 innermost pair very minute. 



Eye strictly lateral, nearer opercular margin than to 

 the end of the snout, 2-2 J in snout, 4J-5 in head, 3-4 

 in the interorbital, measured above or below. Snout 

 acute, depressed. No teeth in the upper jaw; an elongate 

 patch on the sides of the lower jaw. Width of the isth- 

 mus equal to the length of the postorbital part of the 

 head. 



Sides wholly covered by the scutes which overlap on 

 the back behind the dorsal fin, four or five azygous plates 



