OSTARIOPHYSI 



577 



number 3 to 5 only. The fins never bear pungent spines, and 

 the ventrals have 6 to 13 rays. Barbels are absent. In most 

 of the herbivorous forms the brain-case is produced forward to 

 the nasal capsule, whilst in most of the carnivorous forms they 



FIG. 349. Open mouths of Characinidae. (After Miiller and Troscliel.) A, 



trahira ; B, Piabucina argentina ; C, Brycon falcatus ; D, Chalceus a n;/i' //>/"* ; 

 E, Serrasalmo rhombeus ; F, Distichodus nilotici'*. 



are separated by an interorbital septum ; but there are exceptions 

 to this correlation, and as otherwise closely related genera may 

 differ in this respect, I have not been able to make use of the 

 character in defining sub-families. 



VOL. VII 2 P 



