24 THE CYPRINODONTS. 



forehead. Mouth medium, oblique, opening upward. Teeth in a single 

 series, tricuspid. Branchiostegal rays six. Origin of dorsal midway from front 

 edge of orbit to base of caudal. Base of anal below hinder half of that 

 of dorsal, and extending a little farther backward. Anal fin rounded, hardly 

 half as large as dorsal, but extending farther back. Ventrals small, with six 

 or seven rays, or absent. Some have six rays on one side, seven on the 

 other, and in one case there is no trace of the fin. Pectorals broad, rounded, 

 hardly reaching a line from first ray of dorsal to base of ventral. Caudal 

 large, longer than deep at the base, about two thirds as long as head, 

 slightly concave on the hind margin. 



Back greyish brown to brownish ; sides lighter, to silvery on the entire 

 ventral surface. Sides with or without a median series of small blotches 

 separated from the brown of the back and from one another by silvery. 

 In cases each scale has a spot of brown, those on the lateral line being larger 

 and darker. Some have silvery cheeks, others are puncticulate with brown 

 on the sides of the head. The longitudinal bar of silvery above the lateral 

 line when present becomes indistinct in its forward half. Pectorals dusky ; 

 other fins freckled with brownish toward their bases. A darker spot on the 

 basal portions of the hindmost rays of the dorsal ; a darker bar across the 

 bases of the rays of the caudal ; caudal in the majority of cases tipped with 

 a narrow border of black. The specimens described are from the Rio Grande 

 del Norte, the locality furnishing the original description of Baird and 

 Girard, and from the Chihuahua, whence Girard's specimens of C. cximius 

 were brought. The Chihuahua representatives are lighter in colors, but 

 otherwise furnish no reasons for separation from those of the Rio Grande. 



Cyprinodon macularius. 



Cyprimdon macularius B. & G., 1854, P. Phil. Ac, VI, 389 ; Grd., 1859, Mex. Bd. Fish, 68, pi. 37, 

 f. 8-11; Blk., 1860, Gypr., 484; Trosch., 1865, Verz. Wirb. Mex., 104; Jor. & C., 1877, B. Buf. Soc, 

 III, 141; Jor., 1878, B. U. S. G. Sur., IV, 432,-1887, R. U. S. F. Cora., 835 ; Jor. & G., 1882, B. 16 

 U. S. Mus., 330 ; Eig., 1892, P. U. S. Mus., XV, 142; Gilb., 1893, N. Am. Fauna, No. 7, p. 232. 



Cyprimdon californiensis Grd., 1859, P. Pliil. Ac, 157 ; Blk., 1860, Cypr., 484 ; Jor. & C., 1887, B. Buf. 

 Soc, III, 141 ; Jor., 1878, B. U. S. G. Sur., IV, 432, — 1887, R. U. S. F. Com., 835 ; Jor. & G., 1881, P. 

 U. S. Mus., Ill, 457, — 1882, P. U. S. Mus., IV, 49, — B. 16 U. S. Mus., 330 ; Jor. & J., 1882, P. U. S. 

 Mus., IV, 13 ; Eig., 18S8, W. Am. Sci., V, No. 1, p. 3. 



Cyprimdon nevadensis Eig., 1SS9, P. Cal. Ac, (2) I, 270. 



B. 6 ; D. 11-10 ; A. 11 ; V. 7 (rarely 6, or absent) ; P. 15; LI. 27-29 ; 

 Ltr. 11-10 ; Vert. 12+14. 



In the young stages this species resembles C. elegans ; large specimens, 



