98. ACANTHICTTS. 253 



1. Rhinelepis aspera. 

 Spix, Pise. Brasil. p. 4. tab. 2 ; Cuv. fy Val. xv. p. 483. 

 D. 1/7. A. 6. P. 1/6. 

 The origin of the dorsal fin is opposite to that of the ventral. 

 Uniform brown. 

 Rio San Francisco. 



98. ACANTHICUS* 

 Acanthicus, Spix, Pise. Brasil. p. 2. 

 Differs from Rhinelepis in having the interoperculum armed with 

 a bundle of long erectile spines. 

 Brazil. 



1. Acanthicus genibarbis. 



Rinelepis genibarbis, Cuv. 8f Val. xv. p. 484. pi. 453. 

 ? Hypostomus vicinus, Casteln. Anim. Amer. Sud, Poiss. p. 45. pi. 23. 

 fig. 1. 



D. 1/7. A. 6. P. 1/6. 



Snout and fin-rays not spiny ; the length of the pectoral spine is 

 two-ninths of the total ; caudal fin sub truncated. Scutes indistinctly 

 keeled, without serrature. (Val.) 



Brazil ? 



2. Acanthicus hystrix. 



Acanthicus hystrix, Spix, Pise. Brasil. p. 3. tab. 1. 

 Rinelepis acanthicus, Cuv. ty Val. xv. p. 487. 



D. 1/8. A. 6. P. 1/6. 



Head entirely covered with short spines ; the outer fin -rays spiny ; 

 pectoral spine exceedingly long, extending nearly as far backwards 

 as the ventral ; the outer caudal rays prolonged. Each scute with a 

 strongly serrated keel. 



River Amazons. 



This species is founded, at -present, on the single typical specimen 

 in the Museum at Munich ; it is stuffed, and said to be in a bad state 

 of preservation. Rner (Hypostom. p. 254), after an examination of 

 this specimen, asserts that the absence of the second dorsal fin is 

 merely accidental, and, therefore, that it would belong to Cheetostomus 

 (according to our definition of that genus). In his critical remarks 

 on Castelnau's Siluroids ("Wiegm. Arch. 1858, p. 348) he is even 

 inclined to consider it as identical with the Hypostomus spinosus of 

 the latter author, but this has a much shorter pectoral spine. 



* 1. Rinelepis hystrix, Cuv. tf Val. xv. p. 486.— Rah. ? 



