Jordan and Evermann. Fishes of North America. 681 



Intestinal canal as long as body. Dorsal small, far back; distance from 

 its insertion to caudal half that to snout, its first ray about over middle 

 of anal; anal larger and higher than dorsal. Light olive, each scale 

 edged with darker; a very narrow dark streak along sides; top of head 

 dusky ; a more or less distinct triangular bluish-black bar below eye ; 

 sides and belly anteriorly dusky with dark dots; a black blotch on each 

 side of belly, caused by the black internal organs showing through the 

 skin; young specimens often uniform yellowish; fins dusky; the caudal 

 usually with cross series of dots. Length 1| to 2 inches. Males very 

 scarce,* and very small, about i to 1 inch long, the anal process as long 

 as head. The ordinary form, to which the name patruel.is has been given, 

 has usually 8 dorsal rays, a dark suborbital bar, and the fins more or less 

 speckled. Some specimens from Texas have fewer spots, the body and 

 fins nearly plain, and the dorsal rays 6 or 7. These differences are proba- 

 bly of little value. If, however, the distinction holds good, the common 

 form (Delaware to Texas) should stand as subspecies palruells, the name 

 affinis having priority ; the names holbrooki, melanops, and atrilatus being 

 synonyms of patruelis. Marshes and lagoons of the South Atlantic and 

 Gulf coasts, Delaware to Mexico, and north to southern Illinois, in brack- 

 ish or fresh water ; excessively common southward, usually in clear 

 water, but in sluggish rather than running streams. The young are pro- 

 duced in summer, when about i of an inch long.t (affinis, related, to G. 

 holbrooM.) 



Heterandria affinis,l BAIRD & GIRARD, Proc. Ac. Nat. Sci. Phila., 1853, 390, Rio Medina and 



Rio Salado, Texas. (Coll. Clark.) 

 Heterandria patruelis, BAIRD & GIRARD, Proc. Ac. Nat. Sci. Phila., 1853, 390, Rio Sabinal, Rio 



Nueces, and Elm Creek, Texas. (Coll. Clark.) 



Heterandria holbrooki, AGASSIZ, MS., 1854, Charleston, South Carolina. 

 Gambusia holbrooki, GIRARD, Proc. Ac. Nat. Sci. Phila., 1859, 61, Palatka, Florida; GUNTHER, 



Cat., vi, 334, 1866. 

 Gambusia speciosa, GIRARD, Proc. Ac. Nat. Sci. Phila., 1859, 121, Rio San Diego, New Leon, 



Mexico ; said to have fin rays in small number; not counted in description. 



* Of 69 examples from the lower Potomac examined by Dr. Hugh M. Smith, 68 were females. 

 The stomach of one specimen contained algse, diatoms, and fragments of a mosquito. 



f " Mr. A. A. Duly has informed me that he has witnessed the act of copulation and the birth 

 of the young of Gambusia. In coitus the male's head is turned in the direction of the tail of the 

 female, the prolonged anal fin seeming to be thrust into the external opening of the ovarian 

 duct or genital pore of the female, which lies just in advance of the anal fin. The young, when 

 born, are stated by Mr. Duly to be about % of an inch in length, and to be expelled in a single 

 mass, consisting of 8 to 11 young fishes at a single effort. This mass, as eoon as it escapes, is 

 seen to be composed of the infant Gambusias, which at once separate and swim away. No mem- 

 branes seemed to be expelled together with the mass of young, so that it is probable that in this 

 species, as in Anableps and the Embiotocidse, the foetuses rupture the follicles in which they were 

 developed a short time before birth. I say a short time before birth, because our observations 

 indicate that, unlike Anableps and Micrometrvs, the development of Gambusia is essentially com- 

 pleted within the follicles, and no yelk sac remains outwardly visible when the young are set 

 free. My informant also tells me that the parent fishes devoured their young as soon as they 

 were born if they were not separated, by transferring one or the other at once to another 

 aquarium. Fright seemed to hasten or precipitate the parturition, which Mr. Duly tells me 

 actually took place under such circumstances. He also noticed that more than one brood 

 seemed to be produced by the same parent consecutively and during the same season, and he 

 has reason to think that more may have been produced, as his observations only extended over 

 the latter part of summer with adults brought from Cherrystone, in August and September, 

 which he kept in aquaria in the National Museum." (RYDER, Proc. U. S. Nat. Mus., 1885, 

 155.) 



| Gambusia affinis (BAIRD & GIRARD): Body moderately stout. Dorsal and anal fins similar in 

 size and shape, the latter not much advanced. Coloration plain ; dorsal and caudal dotted with 

 black. Head 4; depth 3|. D. 6; A. 8. Girard. 



