CHAEACINID^. 
297 
the oesophagus by a duct in the adult (physostomous); optic nerves 
decussating; intestine without spiral valve ; reproductive organs 
with efferent ducts. 
Synopsis of Families. 
Preinaxilla and maxilla usually entering the 
upper border of the mouth ; teeth usually 
on margin of jaws, and lower pharyngeals 
not falciform ; symplectic bone present; no 
barbels; adipose dorsal fin usually present; 
scales, but no bony scutes. Chaeacinid^ (p. 297). 
Premaxilla excluding maxilla from upper border 
of mouth ; jaws toothless, but lower phar¬ 
yngeals falciform and strongly toothed; 
symplectic bone present; barbels frequent; 
no adipose dorsal fin; scales, but no bony 
scutes . Cyprixid^ (p. 299). 
Preraaxilla almost alwavs excluding: maxilla 
from upper border of mouth; den^lition 
very variable, but lower pharyngeals rarely 
falciform: no symplectic bone; barbels 
present; adipose dorsal fin usually pre¬ 
sent ; no scales, but often bony scutes .... Silueid.® (p. 324). 
Family CHARACINID^. 
Supraoccipital bone prominent, but not completely separating the 
well-developed parietals in the median line; squamosal suturally 
united with parietals and completely covering the otic bones except 
behind; cheek-plates usually well developed. Symplectic bone 
present; premaxilla small and maxilla relatively large, both entering 
the upper border of the mouth; teeth variable, more or less acu¬ 
minate, chiefly on the premaxilla, maxilla, and dentary bones; lower 
pharyngeals not falciform. No barbels. Opercular apparatus com¬ 
plete, but few branchiostegal rays. Pectoral arch with separate 
supraclavicle; a single dorsal fin usually followed by a small 
adipose dorsal on the tail. Trunk covered with scales, but no bony 
scutes. 
No extinct genera of this family are known with certainty. Th e 
existing forms are distributed in the freshwaters of tropical 
America and Africa, attaining their maximum development in 
South America, where there are no C 5 "prinoids. 
The structure of the Characinoid skull is described by M. Sage- 
mehl, Morphol. Jahrb. vol. x. (1885), pp. 1-119, pis. i., ii. 
