698 Bulletin 47, United States National Museum. 



as in Fundulus, the profile scarcely rising to front of dorsal. Teeth small, 

 in two well-separated series, those of the inner row small, close-set, not 

 trifid. Fins all low and short ; pectoral 1 in head ; longest dorsal ray 1 ; 

 caudal truncate, ly ; dorsal in female inserted over middle of anal, behind 

 anal in male. Males scarce, apparently smaller than females. Female 

 greenish above ; sides with violet sheen ; 3 or 4 black crossbars, usually very 

 distinct, sometimes obsolete in large examples ; one or two oblong spots 

 before these in the place of other bars ; last ray of dorsal with a trace of a 

 dark ocellus ; fins otherwise plain ; a dark streak along lower edge of cau- 

 dal peduncle, and another like a pencil mark along middle of sides under 

 the scales. Males without crossbars and with the lower fins reddish. 

 Length 2 inches; very abundant in the clear waters of Rio Presidio, a 

 mountain stream of Sinaloa, 20 miles south of Mazatlan. Many speci- 

 mens obtained. 



Pcecilia presidionis, JORDAN & CULVER, MS., Fishes of Sinaloa, 1895, Rio Presidio, Sinaloa. 

 (Type, No. 2687. Stanford Univ. Mus. Coll. Hopkins Expedition.) 



319. MOLLIENISIA, Le Sueur. 



Mollienisia, LE SUEUR, Journ. Ac. Nat. Sci. Phila., n, 1821, 3, plate in, (latipinna). 



Body rather stout. Mouth small ; mandible very short, its bones not 

 united, the dentary being movable ; both jaws with a narrow band of 

 small teeth, besides an outer series of long, slender, movable teeth, which 

 are curved and slightly compressed, placed on the outer edge of the jaw. 

 Branchiostegals 5. Scales large. Anal fin behind the dorsal, the anal of 

 the male being modified into an intromittent organ j caudal fin alike in 

 the two sexes, or the lower angle very slightly produced in the male, 

 suggesting Xiphophorus ; dorsal fin highly elevated in the male, its base 

 elongate, of 12 or more rays. Intestines elongate, with numerous convo- 

 lutions. Vertebra 17 + 13 30. Small mud-eating fishes, of variegated 

 colors, found from Carolina to Mexico, in the coastwise swamps. The 

 genus is scarcely distinct from PtmZta, differing only in the larger dorsal 

 and the gayer coloration of the male. The species are closely related, and 

 are perhaps all forms of the widely distributed and variable Mollienisia 

 latipinna. (Named for Mollien, French minister of finance, a patron of 

 Pe"ron, the friend and scientific associate of Le Sueur.) 

 a. Dorsal rays 12 or 13. 



b. Insertion of anal behind front of dorsal; a round black spot on upper half of base of 



caudal; each scale edged with dark; dorsal with 2 or 3 series of black spots. 



JONESI, 1038. 



bb. Insertion of anal under front of dorsal; each scale of back with a brown spot; dorsal 

 spotted. FORMOSA, 1039. 



aa. Dorsal rays 13 to 15; dorsal fin in male much elevated and with series of spots; dorsal 

 beginning in advance of anal; scales with dark spots. 



c. Scales 26 to 28-10; dark spots on scales forming lengthwise stripes along back and side ; 



caudal rounded. LATIPINNA, 1040. 



cc. Scales 30-10; dark spots chiefly on posterior part of body; lower angle of caudal pro- 

 duced in adult male. PETENENSJS, 1041. 



1038. MOLLIENISIA JONESI, Gunther. 



Head 4 ; depth Si to 4. D. 12 ; A. 10 ; scales 29-9. Eye shorter than 

 snout. 4 in head, 2 in interorbital width ; length of dorsal fin i distance 



