16 ON THE SPECIES OF THE GENUS ANOSTOMUS. 
ittaiHus will not permit its admission. Apparently it is the 
young of Rhytiodon argenteo-fuscus. The fourth tooth on 
each side in that species is very small and from its position 
against the third is not readily discovered. The teeth of the 
species of Rhytiodon differ considerably, and Kner's figures 
of those of R. microlepis do not Avell represent those of 
R. argenteo-fuscus, which latter agree somewhat well with 
those of 8. Sagittarius as described. Aside from the six 
teeth on the mandible there is nothing in the description 
that will separate Sagittarius and argenteo-fuscus. The 
differences between Rhytiodus and Anostomus seem too 
irreat to allow of brin<?ini>: them tooether as subojenera. 
In the following table are indicated the different divis- 
ions of the genus Anostomus with their contents. 
Snout elongate, narrow, sub-circular in cross section ; 
mouth directed upward, lower teeth long, narrow, 
crenulate . . (Anostomus). 
series of scales 4 from L.l. to D. ; 
flank with two longitudinal bands sahnoneus. 
series of scales 6 from L.l. to D. ; 
flank with two or more spots . irimaculatus. 
Snout broad, sub-elliptic in cross section ; 
mouth directed obliquely upward and forward, 
lower jaw longer ; 
lower teeth broad, truncate or chisel-shaped 
(ScHIZODONTOrSIs) . 
series of scales 5 from L.l. to D. ; 
a band along the flank . . . tceniatus. 
series of scales 6 from L.l. to D. ; 
a band along the flank ; 
transverse bands none . . proximus. 
transverse bands four . . . varius. 
series of scales 7 from L.l. to D. ; 
a band alon<^ the flank . . . orinocensis. 
