254 MEMOIRS OF THE CARNEGIE MUSEUM 



ff. Anal truncate, the highest ray not reaching the base of the last; scales entire; teeth in both 



jaws entire Chilodus. 



666. Teeth on the lower jaw none, or else confined to the sides of the jaw; gill-arches normal; jaws firm. 



(Cf. 6666.) (Hemiodontina.) 



(j. No fontanel; teeth of the upper jaw pectinate, directed backward, their margins in a straight 



• transverse line, teeth of the lower jaw confined to the sides Parodon. 



gg. Large fontanels; teeth in the upper jaw in a crescent, none in the lower jaw. 



h. Scales below the lateral line of the same size as those above it Hemiodus. 



hh. Scales below the lateral line larger than those above it Anisitsia. 



6666. Teeth well-developed in both jaws, fixed. 



i. Caudal forked (Cf. Hydrolicus). 



j. Teeth truncate, notched, or denticulate; or, if conical, the species small, and without an adipose 



fin. 



k. Teeth conical; no adipose fin; no fontanel; mouth short, oblique, cyprinodontiform; two 



series of teeth in the lower jaw. (Pyrrhuh'iniur.) 



I. Premaxillary with two series of teeth Pyrrhulina. 



kk. Not as under k. 



m. Ventral edge without serrse. 



n. Preventral area not expanded; pectorals small. 



o. Premaxillary and dentary each with a single series of teeth. 



p. No frontal fontanel, posterior fontanel, if present, minute; adipose fin 



present or not. ( Nannostomatince.) 



q. Skull truncate; no occipital process; no fontanel; teeth usually 



incisor-like, notched at tips; no lateral fine. 



r. No adipose fin; teeth broad at tip, with five equal points. 



Nannostomus. 

 rr. Adipose fin well-developed. 



s. Pectorals normal; teeth with five equal or subequal 



points Pcecilobrycon. 



ss. Pectorals fleshy flaps, edged with filaments; teeth three- 



to five-pointed, the middle point much the longer. 



Archicheir. 



qq. A triangular occipital process; a small circular occipital fontanel; 



adipose fin well-developed; lateral line complete; teeth 



usually three-pronged Characidium. 



pp. A large frontal and (usually) a parietal fontanel. 



t. Gill-membranes united, usually joined to the isthmus; mouth 



small, with little or no antero-posterior extent. (Ano- 



stomatinw.) 



u. Teeth of the upper jaw serrate or multicuspid. 



v. Snout elongate, subcircular in cross-section; mouth 



minute, vertical; gill-membranes joined to the 



isthmus Anostomus. 



vv. Snout elliptical in cross-section, not produced; the mouth 



terminal Schizodon. 



mi. Teeth of the upper jaw serrate in young, truncate in adult; 



mouth directed obliquely upward. . Schizodontopsis. 



