THE CYPRINODONTS. 45 
Cnesterodon scalpridens sp. n. 
Plate V. Fig. 12, teeth; Plate VIII. Fig. 17, male. 
B. 5; D.7; A. 9; V.6; P. 11; Ll. 28-29; Ltr. 7; Vert. 14+15. 
Elongate, moderately compressed, depth and length of head about equal, 
one fourth of the length, without the caudal. Snout short, blunt, rounded, 
not as long as the eye. Mouth narrow, oblique, directed upward ; lower jaws 
longer, rather firmly joined; upper short, protractile. Teeth chisel-shaped, 
broad and close together in the outer series; inner series scattered in a 
band, small, tricuspid. There are eight incisors on each mandible. Eye 
large, longer than the snout, about three times in the head, or one and one 
half times in the forehead. Dorsal origin opposite that of anal, midway from 
occiput to base of caudal. Ventrals small, reaching the anal. Pectorals 
elongate, reaching the bases of the ventrals. Caudal large, longer than the 
head, subtruncate or slightly convex. Anal of male modified, longer than 
the head, much advanced. In this sex the second rays of the ventrals also 
are elongate. Scales large, intestine long. 
Light olivaceous, edges of scales darker, lower half of cheek and belly 
silvery to golden. A faint streak of silvery, on a single row of scales, be- 
tween the opercle and middle of the base of the caudal, frequently contain- 
ing a black line. Top of head dark; top of snout light. Fins uniform, or 
dorsal puncticulate toward the base. The largest females measure one and 
one eighth inches ; the largest males three fourths of an inch. 
Amazon basin: Santarem; Obidos; Tapajos; Villa Bella; Trombetas. 
GIRARDINUS. 
Girardinas Poey, 1855, Mem., I, 383, $90,—1861, Mem., IT, 383 (part), — 1868, Repert., IT, 411 
(part); Blk., 1860, Cypr., 481, 484 (part), — 1863, Atl, ITI, 139; Gth., 1866, Cat., VI, 351 (part). 
Outlines similar to those of Gambusia. Body compressed, caudal pedicel 
deep, body cavity nearly half of the total length. Head depressed, broad 
and flattened on the crown. Snout broad, short; chin short, steep. Mouth 
wide, directed upward ; jaws short, weak, loosely joined, lower longer, upper 
shorter, protractile. Teeth slender, movable, hooked, contracted at the 
base, broadened, spatulate or shovel-shaped, toward the apex, in a single 
series on each jaw without or with a few very small pointed teeth in bands 
behind them. Branchiostegal rays five. Dorsal fin behind the middle of 
