THE CYPRINODONTS. 89 



longer. Eye large, longer than snout, three eighths of head, two thirds of 

 forehead. Dorsal rays shorter than those of anal, origin about midway from 

 eye to end of caudal, over the third or fourth ray of anal. Anal of the 

 female with fourth and fifth rays prolonged in a sharp angle and the outer 

 border concave. On younger females the angle is not so prominent. Pec- 

 toral reaching over six scales. Caudal broad, longer than head, rounded on 

 hind margin. Scales large, twelve or thirteen between occiput and dorsal, 

 especially wide on the flank. 



Olivaceous to yellowish, edges of scales darker, crown dark, belly and 

 lower half of head light to whitish or silvery. Six to ten short, vertical 

 spots of darker in a series along the middle of the side, with or without spots 

 of light color on single scales in the interspaces. A black spot on the base 

 of the anal. Dorsal and caudal plain, or transversely clouded, the tip of 

 the fin being dark. 



The specimens described were secured along the Panama Railroad 

 between Gorgona and Matachin. 



'o"- 



Gambusia tridentiger sp. n. 



Plate IV. Fig. 10, teeth. 



B. 6 ; D. 8-7 ; A. 10 ; V. 6 ; P. 12 ; LI. 28-30 ; Ltr. 8 ; Vert. 14 + 17. 



Form similar to that of Gambusia Holbrookii. Head short, equal to depth 

 of body at the anal, two ninths of the length to the base of the caudal or two 

 elevenths of the total, slightly arched across the forehead. Snout short, not 

 as long as the eye, narrowed and rounded forward, blunt. Mouth medium, 

 directed obliquely upward ; lower jaws shorter than in G. Holhroohii, longer 

 than the upper, firmly united ; upper short, narrow, protractile. Teeth 

 in the outer series larger, strongly hooked, pointed, broadened somewhat 

 toward the apex ; inner series very small, in bands, tricuspid as in Poecilia ; 

 pharyngeal with a shoulder. Eye large, longer than snout, one half of fore- 

 head, one third of head. Fins small, excepting the caudal. Dorsal smaller 

 than anal and farther back, origin about midway from occiput to end of cau- 

 dal, nearly above the hindmost anal ray, seventeen or eighteen scales from 

 the head. Anal origin midway from snout to end of caudal ; it is farther 

 forward on the male, between the ventrals, and the fin is modified to form a 

 pointed intromittent organ about one third as long as the entire fish. Cau- 

 dal deep, as long as the head, rounded on the hind margin. Scales large, 



12 



