678 Bulletin 4.7, United States National Museum. 



309. PSEUDOXIPHOPHORUS, Bleeker. 



Pseudoxiphophorus, BLEEKER, Ichthyol. Ind. Prodr. Cypr., 483, 1860, (bimaculatus). 

 Pcecilioides, STEINDACHNER, Sitzgsber. Akad. Wiss. Wien, 1863, 176, (bimaculatus).] 



This genus has the general characters of Gambusia, differing in the 

 larger size of the dorsal fin, which has 13 to 16 rays instead of 6 to 10. 

 Anal fin short, less advanced in the male than in Gambusia. The species 

 reach a much larger size than those of Gambusia. The males, as in Gam- 

 busia, are smaller and less numerous than the females. Mountain streams 

 of Mexico. (i/>U(%, false ; Xiphophorus.) 



996. PSEUDOXIPHOPHORUS BIMACULATUS (Heckelj. 



Head 4; depth 3f ; eye longer than snout, 3i in head. D. 12 or 13; 

 A. 10 ; scales 30-8. Head broad and flat, its width between the eyes 2 

 in length. Lower jaw projecting. Anal process ending in a small hook. 

 Length of dorsal equal to head, its front in advance of front of anal. 

 Color light brown, each scale above and back of abdomen with a dark- 

 brown crescent ; all the scales, fins, and mouth parts profusely spotted 

 with brown ; a black spot behind upper end of gill opening and a round 

 blackish spot on upper half of root of caudal ; a black bar composed of 

 black spots at base of dorsal and anal ; a second series of dark spots 

 on dorsal not quite corresponding to the first series. Length 3 inches. 

 Central Mexico, generally abundant ; here described from numerous speci- 

 mens from Rio Blanco, at Orizaba, where it is abundant in the swift waters 

 of mountain streams. This is the only species thus far known in Rio 

 Blanco above the cataracts. (Woolman.) (bimaculatus, two-spotted.) 



Xiphophorus bimaculatus, HECKEL, Sitzgsber. Akad. Wiss. Wien, 1848, 196, Mexico. 

 Pseudoxiphophorus reticulalus,* TROSCHEL, Miiller's Reise Mexico, in, App. 638, 1865, no locality; 



GUNTHER, Cat., vi, 333, 1866; JORDAN & GILBERT, Synopsis, 344, 1883. 

 PaeudoxiphopJiorus bimaculatus, GUNTHER, Cat., VI, 332, 1866; JORDAN & GILBERT, Synopsis, 344, 



1883; WOOLMAN, Bull. U. S. Fish Comm., xiv, 1894, 65. 

 Pcecilioides bimaculatus, STEINDACHNER, Sitzgsber. Akad. Wiss. Wien, 1863, 176. 



310. GAMBUSIA, Poey. 



(GUAJACONES.) 

 Gambusia, POEY, Memorias, i, 382, 1855, (punclata). 



Body moderately elongate, becoming deep in the adult female. Mouth 

 moderate, larger than in Pceeilia, the lower jaw projecting, the bones well 

 joined ; both jaws with a band of pointed teeth which are not movable ; 

 snout not produced. Eyes normal, not divided. Scales large. Gill open- 

 ings not restricted. Dorsal and anal fins both rather short and small, 



* Pseudoxiphophorus reticulatus, TROSCHEL. Our specimens of this nominal species show the 

 following characters: 



Snout broad, spatulate, the lower jaw projecting. Eye equal to snout, 3% in head, 2 in inter- 

 orbital space. Anal process in male 1% head with a slight curve at its tip. Caudal peduncle 

 short. Anal fin inserted in front of dorsal. Dorsal long, its length 3 in body. Coloration as 

 in P. bimaculalus, but darker and more profusely dotted with brown. A large black spot on 

 upper half of root of caudal, and traces of another behind gill opening. Occiput and snout 

 dark brown. Scales on back and sides with a dark-brown crescent. These do not appear on 

 scales of lower parts as in bimaculatus; dorsal fin with dark -brown cross streaks made of dark spots. 

 Fins, scales, cheeks, and ppercles profusely dotted with brown. Head 3%; depth 4. D. 15; A. 8; 

 scales 31-8. Length 2% inches. Hitherto known from one specimen. Here described from two 

 males and one female from Ilio Blanco at Orizaba, collected by A. J. Woolman. This form 

 occurs in company with P. bimaculatus; the two can scarcely be separated, and are probably not 

 really different, but, as Mr. Woolman has already suggested, simply extremes of variation. 



