126 FIELD COLUMBIAN MUSEUM ZOOLOGY, VOL. V. 



Northern Mexico, in the basin of the Rio Grande. 

 . Head $]/$', depth 2 to 2^3; D. 9; A. 8 or 9; scales 12-28. Body 

 deep, compressed; snout bluntish; interorbital convex, 2*^ in head; 

 eye equals length of snout, 3% in head, origin of dorsal midway be- 

 tween base of caudal and preorbital ; base of dorsal i V z in head ; pec- 

 toral iy$ in head; ventral 2^; caudal fin truncate; least depth of 

 caudal peduncle i^ in head. 



Color of males dark brownish with from 6 to 10 rather indistinct 

 vertical bars ; caudal plain with a black margin ; anterior half of dorsal 

 yellowish, its last rays dark; pectorals, ventrals, and anal tipped 

 with black; females lighter, marbled with darker, which has a ten- 

 dency to form cross-bars, and also an indefinite lateral band ; dorsal and 

 anal with a black spot on last rays. Length 2.50 inches. 



This species spawns in July. 



115. Cyprinodon macularius Baird & Girard. 



Cyprinodon macidarius Baird & Girard, Proc. Acad. Sci. Phila., 

 1853, 389; Rio San Pedro, Arizona: Gilbert & Scofield, Proc. 

 U. S. Nat. Mus., 1898, 498; spring-fed pond at Lerdo. Mexico. 



Basin of the Rio Colorado. 



Head 3 to 3^; depth 2 to 2g ; D. 9 to n ; A. 10 or n ; scales 24 or 

 25. Body of adults deep, the young more slender; length of snout 

 about equaling diameter of eye, about 3^3 in head; origin of dorsal fin 

 midway between base of caudal and occiput. 



Color variable; males with back and sides uniformly dusky, the 

 lower parts lighter; all of the fins in most brightly colored individuals 

 broadly margined with black ; females with the lower half of the sides 

 as well as belly lighter, often silvery white ; the sides crossed by black 

 bars, which are wide along the middle of the body, but becoming much 

 narrower than the interspaces on the lower half of the sides, these 

 bars varying in number and size and often alternating with narrower, 

 fainter, and shorter ones; fins light; the dorsal either with or without 

 a black blotch on its posterior ravs; the males sometimes show dusky 

 bars. (Gilbert.) 



116. Cyprinodon latifasciatus Garman. 



Cyprinodon latiiasciatus Garman, Bull. Mus. Comp. Zool., 1881, 

 92 ; Pairas, Coahuila, Mexico: Jordan & Evermann, Bull. 47, U. 

 S Nat. Mus., 1896, 676. 



Rio Nasas and the headwaters of the Rio Mezquital. (Labor; 

 Durango.) 



Head 3^; depth 2^3 ; D. 9; A. 9 or 10; scales 11-26. Body robust, 

 deep, moderately compressed; head short, snout bluntish; mouth 



