SOUTH AMERICAN NEMATOGNATHI. 429 



culatum and duodechnalis , and the name etentaculatuTn 

 should be retained. 



Depth a little less than the width. Head broad, high; 

 occipital roof-shaped, interorbital flattish. Snout in the 

 old rather pointed, its tip naked; interopercle erectile, 

 with a few shortish spines at its tip. 



Orbit 3-3J in the snout, 6-6| in the head, 21-2| in 

 the interorbital. Temporal keel distinct; posthumeral 

 keel strong; all the lateral scutes with a strong median 

 keel; ventral surface naked in the young, granular in 

 the adult. 



Base of the dorsal fin less than its distance from tip 

 of snout, its height 1|^ or more times in its base. 



Caudal obliquely emarginate, its outer rays thickened 

 and slightly prolonged. 



Pectoral reaching beyond base of ventrals; ventrals 

 little, if at all, beyond origin of anal fin. 



Light brown, spotted with darker, the belly spotted 

 with lighter; membrane of adipose fin black; outer cau- 

 dal rays barred, the remainder of the fin dusky; other 

 fins with very large dusky spots, the light background 

 forming reticulating lines. 



Head 24-2f ; D. I, 11; A. 27-28. 



Four specimens .09-. 22 m. Rio San Francisco, below 

 the falls. 



400. Pterygoplichthys gibbiceps. 



Ancistrus gibbiceps Kner, Hypostomiden, 252, pi. 5, fig. 2, 1853 (Rio 



Negro). 

 Pterygoplichthys gibbiceps Giinther, v, 252, 1864 (copied); Eigeum. 



& Eigenm. Proc. Gal. Acad. 2d Ser. ii, 44, 1889 (Coary; Teffe; 



Porto do Moz; Lago Alexo; Ciidajas; Lake Hj^auuary; Santa- 



rem; Tabatinga; Lago do Maximo: Jutahy; Villa Bella; Silva; 



Obidos). 

 Chcttostomus gibbiceps SteiDdachuer, Flussfische Siidamerika's, ii, 



114, pi. iv, fig. 1, 188r(Obidos; Villa Bella; Coary; Jatiiarana; 



Gurupa; Tabatinga; Jutahy; Silva, Lake Saraca; Lake Hyauu- 



ary; Lago Alexo). 



