SOUTH AMERICAN NEMATOGNATHI. 129 



§ Rhamdella subg. nov. 



Type, Bhemdia eriarcha, nov. 



Fontanel continued to the occiput, a bridge across it be- 

 hind the orbit. 



31. Rhamdia microcephala (Keiuhardt). 



32. Rhamdia notata (Schomburgk). 



33. Rhamdia eriarcha sp. nov. 



One specimen .26 m. in length. Dom Pedro. Rio Grande do Sul. 



Body elongate, slender, the width below the dorsal spine 

 less than the depth. Head long, pointed, entirely covered 

 with skin; the fontanel continued to base of occipital 

 process, which reaches about half way to dorsal spine; the 

 head flattish above, snout long and pointed; the width at 

 angle of mouth 2| in length of head. 



Eye large, 2 in snout, 4.^ in head, its center about one- 

 fourth nearer posterior margin of opercle than to tip of 

 snout, the interorbital less than a diameter of the eye. 



Maxillary barbels reaching posterior edge of opercle; 

 post-mental barbels not to gill-opening if drawn horizontally 

 backward. 



Upper jaw produced; lips thick, strongly plicate; inter- 

 maxillary baud of teeth deep and narrow, the teeth minute; 

 no teeth on vomer or palatines; teeth of the mandible 

 similar to those of the upper jaw, in a narrow band which 

 tapers backward. 



Gill-membranes separate to below center of eye; gill- 

 rakers l-|-5. 



Distance of dorsal fin from tip of snout % in the length; 

 first ray of dorsal scarcely spine-like, smooth, its height, in- 

 cluding filament, If in length of head; highest ray I5 in 

 head, higher than the length of the fin. Adipose fin 2^ in 

 the length, distant from the dorsal fin as far as the base of 

 the dorsal fin is long. 



Caudal forked to its base, the upper lobe greatly pro- 



