FiSHEis OF THE Order Cyprinodontes 7 



IV 



An Analysis of the; Genera of the Poeciliidae 



A^. — Lower edge of caudal peduncle rounded, with a median series of normal scales. 



Pelvic fins well developed in both sexes, and inserted behind the base of the 



pectorals. 



B^. — Pelvic fins alike in the two sexes. Gonopodium elongate; the two halves of 



posterior branch of ray 5 not separated. 



C^ — Raj's of the gonopodium not imbricated so as to form an enclosed tube, 



all lying strictly in the same plane (see figures i, 2, and 4-7). Jaws firmly 



united (except in Girardinus) Gambusiinae. 



D^. — Terminal segment of ray 3 (of anal fin in male ;= first prolonged ray of 

 gonopodium) not forming a specialized transverse process. 

 E^. — Ray 5 and posterior branch of ray 4 each with a small, usually retrorse 

 hook at its extremity ; anterior branch of ray 4 with a thickened node, 

 which is sharply produced, except in Belonesox,- to form the "elbow." 

 (Tribe Oaiubusiini) .'• 

 F^. — Jaws normally formed. Thickened node of ray 4 shorter but more 

 sharply produced, forming a well-defined "elbow" (see figure i). 

 G^. — Ray 3 without erect spinules; serrae of ray 4 less modified, and 

 wholly apicad to elbow; apical processes of rays 4 and 5 scarcely 

 hooked. Dorsal fin more posteriorly inserted (about twice as distant 



from eye as from base of caudal in female) Heterophallus.''' 



G-.— Ray 3 with erect spinules more or less sharply developed; serrae of 

 ray 4 better developed, in part at least and usually wholly proximad 

 to elbow; apical processes of rays 4 and 5 strongly hooked, except in 

 one subgenus (undescribed). Dorsal fin less posteriorly inserted.. 



Gambusia. 



F^. — Jaws produced into a short beak. Thickened node of ray 4 longer and 

 not sharply produced to form a well-defined "elbow" ; ray 3 without 

 erect spinules; serrae of ray 4 sharply developed and wholly proximad 



to thickened node; apical processes of rays 4 and 5 scarcely hooked 



Belonesox. 



E-. — Ray 5 and posterior branch of ray 4 each without a trace of a retrorse 

 hook at or near the tip, the posterior branch of ray 4 not entering into 

 the distal modification of the gonopodium; the anterior branch of ray 4 

 not provided with a thickened node, except in Allogambusia® (see 

 figure 2). 

 H^. — ^Ray 3 without a pair of curved, horn-like appendages ; ray 5 always 

 smooth on posterior edge. (Tribe Heterandriini) .' 

 P. — Ray 3 without developed serrae. Teeth conical (slightly compressed 

 in Heterandria). 

 Ji. — Ray 3 without definite processes of any kind; ray 4 with no trace 

 of an enlarged node resembling the "elbow" of the Gambusiina. 

 K^. — Rays 4 and 5 contiguous distally, or nearly so, never separated 

 by a notch in the membrane; rays 3 and 4 not together support- 

 ing a small knob. 

 L^. — Rays 4 and 5 both entering into the formation of tip of gono- 

 podium. 



® Gambusiini, new name (as a tribe name). 



■f Regan, Ann. Mag. Nat. Hist., (8) 14, 1914, p. 66, fig. A. Haplotype, Heterophallus 

 rachovii Regan, from Vera Cruz, Mexico. 



^The thickened node of ray 4 in Allogambusia is probably of independent origin, 

 as the genus does not otherwise especially resemble the Gambusiini, and as the node 

 differs in certain details from the "elbow" of the group. 



• Heterandriini Hubbs, new tribe name. 



