82 THE CYPRINODONTS. | 
cases the scales have a wide posterior edging of black. On some the 
median row on the flank has a wide black tip. A dark patch behind the 
eye is common, as, also, the black blotch on the upper half of the base of 
the caudal. Occasionally a small whitish spot appears on the middle of the 
scale. Fins dusky to almost black; caudal with or without a light trans- 
verse streak behind the black blotch. On very dark colored individuals the 
caudal is nearly black and the blotch is indistinct. 
Attaining a length of four inches. 
Mexico. 
GAMBUSIA. 
Gambusia Poey, 1855, Mem., I, 382, 390, — 1861, Mem., II, 383, — 1868, Repert., II, 209, 410; 
Gth., 1866, Cat., VI, 333, — 1880, Intr., 616; Jor. & G., 1882, B. 16 U. S. Mus., 344. 
Gambusiine Gill, 1894, Mem. Nat. Acad., VI, 133. 
Body rather short and stout; caudal pedicel deep; head depressed. 
Snout broad, blunt. Chin moderately steep. Mouth large, wide, resem- 
bling that of Zygonectes ; mandibles strong, firmly united; intermaxillaries 
shorter, protractile. ‘Teeth conical, in cards, hooked, outer series larger. 
Branchiostegal rays usually six. Dorsal originating behind the middle of 
the body; anal origin farther forward, fin more advanced and modified 
to form an intromittent organ in the male. Intestine rather short. 
The separation of this genus from Heterandria seems to be fully war- 
ranted by the shape of the teeth, the structure of the mouth, the number 
of branchiostegal rays, and other particulars. Unless otherwise specified the 
species are described from females. 
Gambusia Holbrookii. 
Plate IV. Fig. 3, teeth; Plate VIII. Fig 5; Plate XI. Fig. 4-13. 
Heterandria Holbrookii (Ag.) Grd., 1859, P. Phil. Ac., 61. 
Gambusia Holbrookii, Blk., 1860, Cypr., 485 ; Put., 1868, B. M. C. Z., 14; Gth., 1866, Cat., VI, 334; 
Goode, 1880, P. U. S. Mus., II, 118. 
Gambusia patruelis Jor., 1881, P. U. S. Mus., III, 21, —1885, P. U.S. Mus., VII, 322; Ryder, 1882, 
Amer. Nat., Feb., —1886, P. U. S. Mus., VIII, 148, pl. 6-10; Jor. & G., 1882, B. 16-U. 8. Mus., 893, — 
1887, P. U. S. Mus., IX, 26; Jor. & M., 1885, P. U.S. Mus., VII, 235; Gilb., 1890, B. U.S. F. Com., 
228, —1891, B. U. 8. F. Com., IX, 158; Hensh., 1891, B. U. S. F. Com., IX, 374; Bean, 1892, P. U.S. 
Mus., XIV, 92; Smith, 1892, B. U.S. F. Com., X, 69, pl. 20, fig. 1; Woolm., 1892, B. U.S. F. Com., X, 
294, 296, 298, 300, 301. 
Gambusia patruelis holbrookii Jor. & G., 1888, P. U. S. Mus., V, 587. 
Haplochilus melanops Cope, 1870-77, P. Am. Phil. Soc., XI, 457. 
Zygonectes melanops Jor., 1876, Man. Vert., 252; Jor. & C., 1877, B. Buf. Soc., III, 142. 
Zygonectes (Micristius) melanops Jor., 1878, Man. Vert., 264, — B. U. S. G. Sur., IV, 433; Jor. & G., 
1882, B. 16 U. S. Mus., 340. 
Zygonectes atrilatus Jor. & B., 1878, B. 12 U. S. Mus., 84; Jor. & G., 1888, P. U. S. Mus., V, 258. 
Zygonectes (Micristius) atrilatus Jor. & G., 1882, B. 16 U. S. Mus., 340. 
