Family XI. Pceciliid^;. ioi 



oo. Body deep, compressed, depth 27^ to 3 % in page 



length; gill rakers rather short, stiff, about 



20 on the first gill arch; vertebrae 16 + 18=34 Skifjia 141 



nn. Outer series of teeth pointed: anal fin of the 

 male placed well forward and modified into an 

 intromittent organ; species viviparous, 

 p. Teeth in a single series, 

 q. Dorsal fin inserted in advance of the anal . . .Platypcecilus 144 

 qq. Dorsal fin inserted more or less behind the 



front of the anal Heterandria 147 



pp. Teeth in more than one series; dorsal fin in- 

 serted over or in advance of anal, its rays 

 much elevated in the male. 

 r. Dorsal fin short, of less than 7 to 11 rays; 



teeth of the inner series in both jaws entire Poecilia 149 



rr. Dorsal fin long, of 12 to 16 rays. 

 s. Caudal fin normal, alike in both sexes, or 

 with the lower angle merely sharp in the 



male Mollienesia 154 



ss. Caudal fin in the males with its lower lobe 



much produced and sword-shaped Xiphophorus 156 



Subfamily Fundulinae. 

 4:>. Cynodonichthys gen. nov. 



Type, Cynodonichthys tenuis Meek. 



Body elongate, depressed anteriorly, compressed posteriorly; 

 head broad and flat; lower jaw the longer; teeth in villiform bands, 

 a large canine-like tooth on each side in front of upper jaw; a few 

 smaller and similar teeth in front of lower jaw; dorsal fin posterior, its 

 origin over posterior third of anal; margins of caudal fins formed by 

 tips of short basal rays; head entirely scaled. A very peculiar fish, 

 quite unlike any other member of the family, xuvoq dog, od6\> tooth, 

 r/0u<; fish. 



90. Cynodonichthys tenuis sp. nov. 



Type, No. 4643, F. C. M., 1.6 inches in length; El Hule, Oaxaca. 



Head 3^; depth \%; D. 8; A. 11; scales 10-38. Body elongate, 

 depressed anteriorly, compressed posteriorly; head broad, much de- 

 pressed; interorbital flat, 2 in head; snout short, 4 in head; upper jaw 

 the longer; teeth in jaws in villiform bands, upper jaw with a well- 

 developed canine-like tooth on each side ; some of anterior teeth of 

 lower jaw canine-like; eye small, 3% in head; premaxillary pro- 



