120 PROCEEDINGS OF THE ACADEMY OF 



of the male sex, measuring about an inch and a quarter in total length, rather 

 slender in general appearance, and resembling somewhat the same sex in Gam- 

 busia. The anal fin, however, is more slender and deeper than in the latter 

 genus, it being composed of but two developed rays preceded and followed by 

 inconspicuous rudimentary ones. The other fins are so much mutilated as not 

 to allow counting their rays with any degree of certainty. The coloration is 

 the same as in the female sex, just alluded to above. 



LIII. Specimens of a species closely, allied to the foregoing one, were collected 

 in San Bernardino creek, Mex., by Dr. C. B. R. Kennerly, under Major Emory. 

 That creek, it will be remembered, flows westwards of the Sierra Madre, ming- 

 ling its waters with those of the Rio Yaqui, which empties itself into the Gulf 

 of California. 



The largest of these specimens belonging to the female sex measure two 

 inches and a quarter in total length, being therefore of the same size as some 

 of those of the preceding species. Nothing is more alike than the general 

 aspect of these two species ; the present one, however, is more stoutly built. 

 The head constitutes about the fifth of the total length. The caudal fin is pos- 

 teriorly subtruncated. The dorsal and anal fin are inserted somewhat farther 

 back, each beine; provided with eight rays instead of seven ; otherwise the for- 

 mula is the same : D 8 ; A 8 ; C 4, 1, 7, 7, 1, 3 ; V 6 ; P 12. The scales have 

 the same shape and structure, but they are proportionally smaller, than in the 

 preceding species. 



The specimens of the male sex, measure about an inch and a quarter or a 

 little more. They bear the same relations to their females as those of the pre- 

 ceding species. The dorsal fin exhibits likewise eight rays. 



The ground color, in either sex, is of a dark chestnut brown, with black dots 

 at the periphery of the scales, and a lateral black fillet covered by a lateral 

 streak of the width of a scale. A narrow dark streak may also be observed 

 under the peduncle of the tail. In its coloration, therefore, this species does 

 not differ very materially from the foregoing one. The lateral streak alone ap- 

 pears as a more constant feature. 



We shall designate it provisionally under the name of G. sonoriensis. 



LIV. Let it be recalled to mind here, that the mouth in Gambusia is construct- 

 ed after the fashion of Hydrargyra and Zygonectes, and that its gape is horizontal 

 when protracted, and oblique upwards when in a contracted state. Indeed, 

 the affinities between Gambusia and Zygonectes are of the most intimate kind, 

 since in Zygonectes the anterior margin of the anal fin is sometimes situated in 

 advance of the anterior margin of the dorsal. It is true, we find a slight dif- 

 ference between these two genera, in the gape of the mouth when in a pro- 

 tracted condition, and also in the sexes, which assume a different aspect in 

 Gambusia, whilst in Zygonectes the differences between the male and the female 

 are a great deal more restricted. 



The party under Lt. J. G. Parke, on its way home, collected in Caman- 

 che Spring specimens of both sexes of Gambusia nobilis, the male of which we 

 had not observed so far. It has the same general aspect as its female, figured 

 on plate xxxix, of the "Ichthyology of the U. S. and Mex. Boundary," being 

 rather short and deep bodied compared to its congeners. In coloration both 

 sexes agree. The largest specimens of the female sex measure two inches and 

 those of the male one inch in total length. 



LV. Specimens of Gambusia affinis were also collected in San Pedro creek, 

 Tex., and in Dry creek near Victoria, Tex., by Dr. C. B. R. Kennerly, under 

 Major Emory. The male sex measures one and a tenth of an inch in total 

 length, and compares well with the female figured on plate xxxix, of the ' ' Ich- 

 thyology of the U. S. and Mex. Boundary," having the same slender appear- 

 ance and general aspect. The anal finis somewhat deeper than in G. patruelis 

 represented on the plate just alluded to. The color is similar in either sex. 



[April; 



