156 Field Columbian Museum — Zoology, Vol. V. 



opercle and cheek minutely speckled; an orange stripe above opercle; 

 lower parts of head mostly orange ; dorsal with about 5 series of linear 

 blackish, horizontal spots forming interrupted lines; a large roundish 

 dark spot above middle of fin or membrane between each pair of 

 rays ; many round brown spots between these and above them ; caudal 

 with a narrow black margin; dorsal and caudal fins of females oliva- 

 ceous, with indistinct narrow cross bands formed by a series of small 

 dark dots or rays. Length about 3 inches. 



The male of this species with his highly colored dorsal fin is a 

 fish of remarkable beauty. 



(>♦>. Xiphopliorus Heckel. 



Xiphophorus Heckel, Sitzgsber. Akad. Wiss. Wien, 1848, 1, pt. 

 3, 163. (Type, Xiphophorus helleri Heckel.) 



Body elongate, not much compressed; dorsal fin in advance of 

 the anal in females; teeth in two series, the outer enlarged, loose; 

 the lower rays of the caudal fin of the male produced into a long, 

 sword-shaped filament; anal fin of male placed forward and modified 

 into an intromittent organ; alimentary canal in about four coils on 

 right side, its length about twice that of the fish; vertebras 16 + 14 



= 30- 

 KEY TO THE SPECIES OF XIPHOPHORUS. 



a. Anal fin long, with 8 or 9 rays; edges of scales page 



on upper part of body not especially dark, very 

 faint, 

 b. Body slender, its depth 3^3; least depth of 



caudal peduncle 2]4 in head jalapa 156 



bb. Body more robust, its depth 3^ to 3; least 



depth of caudal peduncle 2\ in head helleri 157 



aa. Anal fin short, with 7 rays; edges of scales on 

 upper part of body very dark, making their 

 outlines very distinct montczumce 158 



148. Xiphophorus jalaps Meek. 



Xiphophorus jalapce Meek, Field Col. Mus. Pub. 65, 1902, 107; 

 Jalapa. 



Streams of Central Vera Cruz, at an altitude of about 5,000 feet. 

 (Jalapa). 



Head 4; depth 3^3"; D. 13; A. 9; scales 8-28. Body elongate, 

 not very robust, but with a deep caudal peduncle; head flatfish, de- 

 pressed forward, being wedge-shaped; interorbital broad, convex, 2 

 in head; mouth rather small, lower jaw the longer; outer series of 



