130 ACAXTIIICUS. 



the distinctions which are given in the coispectus 

 generum of the Brazilian fishes are minute, and con- 

 sist almost in the abdomen of the one being naked, 

 while in the other it is covered with minute scales. 

 M. Yalenciennes appears to consider the Acanth. 

 histrix of Spix to be distinct from the species origi- 

 nally described by M. Yandelli, for which he retains 

 the name, giving the other under the title of Rhine- 

 lepis acanthicus. The drawing and specimen before 

 us agree best with the true A. histrix^ that of Van- 

 delli, and as such we provisionally keep it. The 

 outer rays of the tail are represented in the drawing 

 not at all elongated, and do not appear to have 

 been so in the specimen, though it is a little muti- 

 lated. The group of bristling processes before the 

 opercula are much stronger and more elongated, so 

 also is the armature of the first ray of the pectoral 

 fins, and the distribution of the spines on the plates 

 of the sides agree with the description of Yalen- 

 ciennes. On our first Plate, then, we have endea- 

 voured to give a figure of it, adding previously the 

 generic characters from Agassiz. 



Acanthicus Spix. — " Totum corpus aculeatum ; truneus 

 seutis osseis, crassis squamiform bus, distinctis tectis ; 

 abdomen non scutatum. Dentes bi^inflexi per series 

 radiatas (neo circulares) dispositi. Velum labiale cir- 

 culare. Pinna dorsalis unica." 



RiiiNELEPis Spix " Totum corpus limatum ; truneus seutis 



majoribus, imbricatis ; venter seutis minutis discretis 

 tectis. Dentes radiati, apice hamati, primus bisin- 

 flexus, apice fissus. Labium inferius solum velatum, 

 labium supev'us cirrUatum.. Pinna dorsalis uuica." 



