423 ON FISHES FROM THE RIO JURUA. 



This fish is very rare in the Jurua River, and but a single specimen could be procured 

 by Dr. Bach. 



It is a most remarkable form, differing very considerably from any of the species 

 with which we are acquainted. 



48. Rhamphiciithys blochii Kaup. 



49. Steatogenys elegans Stdr. 



The presence of a filament of adipose tissue, similar to the dorsal fin of Sternarchus, 

 in a groove along each side of the mental region, to which attention has been drawn by 

 Steindachner in describing his Rhamphiciithys elegans, warrants, in my opinion, the 

 establishment of a new genus, for which I propose the name Steatogenys. 



50. Sternopygus virescens Val. 



TETRODONTID^E. 



51. Tetrodon psittacus Bl. Schn. 



EXPLANATION OF THE PLATES. 

 PLATE XXXIX. 



PI aty stoma juruense, p. 421, with upper and lower views of head 

 and outline of praemaxillary and palatal teeth, 



PLATE XL. 



Fig. 1. Oxydoras trimaculatus, p. 422. 

 Fig. 2. Oxydoras trachyparia, p. 423. 

 Fig. 3. Oxydoras bachi, p. 423. 

 Fig. 4. Oxydoras elongatus, p. 424. 



PLATE XLI. 

 Fig. 1. Chcetostomus bachi, p. 425. 

 Fig. 2. Acestra gladius, p. 425. 

 Fig. 3. Cetengraulis juruensis, p. 427. 



PLATE XLIL 



Sternarchus tamandua, p. 427, with upper view of head. 



