THE CYPRINODONTS. 49 



tion of the tail is short and high, its least depth being equal to the length of 

 the head or to the distance between doi'sal and caudal. The pectoral extends 

 considerably beyond the root of the ventral, and the ventral reaches the origin 

 of the anal. 



" Brownish olive, with a roundish black spot on the middle of the root of 

 the caudal ; a blackish spot on the middle of the side of the trunk. Dorsal 

 sometimes densely spotted with black ; the lower margin of the anal and the 

 upper and lower margins of the caudal black." 



Mexico. (Gunther). 



We have given above the original descriptions of genus and species. The 

 specimens, two in number, were an inch and a half in length. Until more 

 data are secured it will not be possible to determine the proper classification 

 or affinities. 



MOLLIENISIA. 



Mollienisia Les., 1821, J. Phil. Ac, II, 3 ; Val., 1846, C.V. Poiss., XVIII, 137; Blk., 1860, Cypr., 

 482, 485, — 1863, Atl., Ill, 139. MoUeiiesia Wagn., 1828, Isis, XXI, 1055. Moliiiesia Cuv., 1836, R. An., 

 ed. 3, I, 533 ; Schinz, 1836, Nat. u. Abb., 217 ; Swaius., 1839, Class., II, 190, 311 ; McCl., 1839, J. As. 

 Res., XIX (2), 424; DeK., 1842, N. Y. Fish, 221; Poey, 1855, Mem., I, 382. Molinisea Swaius., 1838, 

 Class., I, 365. Mollinesia Stor., 1846, Syn., 182, — Mem. Am. Ac., II, 434; Ag., 1853, Am. Jour. Sci., 

 XVI, 135; Jor. & C, 1877, B. Buf. Soc, III, 143. Mollie/iesia Ag., 1855, Am. Jour., XIX, 136; Gth., 

 1866, Cat., VI, 347,-1880, Intr,, 617 ; Jor. & G., 1882, B. 16 U. S. Mus., 346. 



Body short, much compressed, caudal pedicel deep ; head depressed 

 crown flattened. Snout short, broad ; chin short, steep. Mouth wide, open- 

 ing upward ; lower jaws short, weak, loosely joined ; upper shorter, protrac- 

 tile. An outer series of slender, oar-shaped, hooked, movable teeth on each 

 jaw, and behind these a band of small, pointed ones. Dorsal large, larger 

 than anal, subject to considerable changes in males. Anal opposed to the 

 dorsal, but usually originating farther back, modified in the male, as in' Poe- 

 cilia, to form a short intromittent organ. Caudal region deep and narrow. 

 Scales large, broad. Intestine long. Type M. latipimia. 



Virginia to Central America. 



This genus is closely allied to Poecilia, with which it agrees in general 

 form, dentition, structure of mouth, and modification of the anal fin. The 

 principal characters on which to base a separation of these genera are the 

 greater size of the dorsal and the greater changes effected by growth in 

 Mollienisia. 



