]93 



HYDROCYON. 



The genus Ilydrocyon seems to exist in consider- 

 able abundance in many of the rivers, though few 

 specimens were procured in Guiana ; * and in tlie 

 Brazilian fishes, Raphiodon of Agassiz takes its 

 i:)lace. He has characterised it, 



" Raphiodon, Agassiz. — Caput parvum, compressissimum, 

 Oculi magni laterales. Os maximum oblique dcscen- 

 dens. Dontcs validissimi, acutissime, cum minoribus 

 alteniautcs, in ossibus intcrmaxillaribus minoribus mar- 

 ginem tantum anteiiorem maxilla; superioris confor- 

 mantibus, et in mandibula ; ossa maxillaria superiora 

 longa, angusta. Lateralia dcntibus minoribus obsita. 

 Ling-ua magna, promincns, apiee libera. Apertura 

 brancliialis maxima. Membrana branchiostega radiis 4 

 gracilibus. Caput clongatum, compressum, squamis 

 parvis abductum ; abdomen acute carinatum sed non 

 serratum. Pinnte pcctorales magnto, ventralcs parvce, 

 analis latissima." 



Both the specimens which are figured (but under 

 the name of Cyonodun (have very strongly armed 

 jaAVS and a wide mouth ; the ventrals very small ; 

 while the anal fin covers more than a third of the 

 lower line of the fish. In many of these w^e have 

 some dark spot or other marking, as we have seen 

 so frequently among the fishes from those parts of 

 South America. 



* See Vol. I. p. 257. 



