44 THE CYPRINODONTS. 
the support of the anal fin, Plate VIIL Fig. 16. Intestine elongate. Type, 
C. decemmaculatus from the Uruguay River. 
Cnesterodon decemmaculatus. 
Plate V. Fig. 13, teeth; Plate VIII. Fig. 16, male. 
Pecilia decemmaculatus Jen., 1842, Zool. Beagle, Fish, 115, pl. 22, fig. 1; Blk., 1860, Cypr., 486; Eig., 
1894, Ann. N. Y. Ac., VII, 637. 
Peecilia gracilis Val., 1846, C-V. Poiss., XVII, 183; Blk., 1860, Cypr., 486. 
Girardinus decemmaculatus Gth., 1866, Cat., VI, 355; Hens., 1868, Arch. f. Nat., XXXIV, 364, — 
1869, XXXV, 89; Perug., 1891, Ann. Mus. Civ. Gen., X (2), 653; Hig., 1891, P. U. S. Mus., XIV, 65. 
B.5; D.8; A. 10-9; V.6; P.12; Ll 31; Ltr. 8-9; Vert. 14+18. 
This is evidently a small species; females of one and one eighth 
inches bear well developed young. The shape of the body bears some 
likeness to that of Heterandria formosa, on Plate XI. The length of the 
head is equal to the depth of the body, and is four fifteenths of the 
distance from snout to base of caudal. Crown slightly arched trans- 
versely. Snout short, about three fifths of the eye, broad, blunt. Mouth 
moderately wide, opening upward; lower jaws longer, somewhat firmly 
joined; upper short, protractile. Outer series of teeth rather broad and 
shovel-shaped, hooked; inner in a band, not numerous, very small, pointed, 
apparently with a slight expansion at each side near the apex; pha- 
ryngeal slender, hooked. Eye large, longer than snout, two fifths of head, 
three fourths of forehead. Dorsal origin nearly midway from eye to base 
of caudal, about opposite that of anal. On males the anal is farther for- 
ward, and modified into a long intromittent organ. On the specimen ex- 
amined this organ is bladelike and without hooks, about one and one half 
times the length of the head or less than half as long as head and body with- 
out the caudal. Ventrals very small, rays sometimes five. Pectorals reach- 
ing the middle of the ventrals. Caudal elongate, deep, convex. Scales large, 
twelve between occiput and dorsal. 
Light olivaceous, cheeks and throat silvery, belly silvery to golden. A 
series of irregular, more or less indistinct spots of dark color between the 
upper angle of the gill-opening and the middle of the caudal. Edges of 
scales darker. Tip of caudal sometimes darker. Some have a narrow streak 
of dark color on the middle of the caudal pedicel. In cases dorsal and anal 
are darker near their extremities. 
Uruguay River; Maldonado. 
