66 



UNITED STATES AND MEXICAN BOUNDARY. 



Family CYPEINODONTIDAE. 



CYPEINODON, Lacep. 



The genus Cyprinodon is composed of small fishes, more or less sub-elliptical in their general 

 appearance, with no other differences between the sexes, except that in the female the body is 

 occasionally more elongated than in the male, and approaching to a sub-fusiform shape. The 

 position and shape of the fins are nearly alike, the dorsal alone being somewhat higher in the 

 male than in the female, without, however, approaching to anything like that of Poecilia. 

 The caudal is sub-truncated upon its posterior margin. The ventrals are small. The head is 

 rather well developed and anteriorly rounded off. The teeth are elongated, broadest at the 

 crown, which is trilobed. The gill apertures are continuous under the throat. 



These fishes inhabit the brackish waters, and are especially numerous in the warm region of 



the temperate zone. 



1. CYPRINODON ELEGANS, B. & G. 



■ 



Plate XXXVII, Figs. 1—7. 



Spec, Char. — The general form differs according to the sexes ; it being sub-fusiform in the female and sub-elliptical in the 

 male. The head constitutes about the fourth of the total length. The diameter of the eye enters about four times in the sides 

 of the head. The dorsal fin is longer than high ; its anterior margin being equidistant between the extremity of the snout and 

 the Lase of the caudal ; its upper margin rounded off. The caudal, which forms about the seventh of the total length, is 

 posteriorly sub-truncated. The origin of the ventrals is situated opposite the anterior margin of the dorsal fin. 



Syn. — Cyprinodon elegans, B. & G. in Proe. Acad. Nat. Sc. Philad. VI, 1853, 389. 



The dorsal region is deep bluish black, the sides of the body being variegated with bluish 

 black and olive. The posterior edge of the caudal fin is black in the male. A black spot, 

 more conspicuous in the female than in the male, may be observed at the posterior margin of 

 the dorsal fin. 



D 11 j A 10 ; C 3, 1, 8, 8, 1, 2 ; V 6 ; PH. 



Plate XXXVII, fig, 1, represents the female sex of Cyprinodon elegans, size of life. Fig. 2 

 is an outline from above. Fig. 3, a section across the region of greatest depth. Fig. 4, the 

 male sex of the same species, also size of life. Fig. 5, its teeth. Fig. 6, an outline from 

 above. Fig. 7, a transverse section. 





i 



List of specimens. 



atal. 

 No. 



686 



6<s7 



No. of 

 spec. 



Sex. 



21 



11 



s 



Locality 



Cainanche Springs, Rio Grande 

 del Norte (Rio Bravo). 



When 



collected. 



1851 



1851 



Whence obtained. 



Col. J. D. Graham... 



do 



Nature of 

 specimen. 



Alcohol ic. 



do 



Collected by 



John H. Clark 



do 



I 



