142 Field Columbian Museum — Zoology, Vol. V. 



Basin of the Rio Lerma. 



Head 4; depth 2-f ; D. 16; A. 15; scales 12-32. Body deep, much 

 compressed; interorbital slightly convex, 2 in head; snout short, 

 rather pointed, 4 in head; mouth small, lower jaw slightly the longer; 

 eye large, 3 in head; dorsal fin slightly in advance of the anal, its origin 

 midway between base of caudal and eye ; base of dorsal 1 % in head ; 

 height (in female) 1 ]A, , somewhat higher in the male ; anterior portion 

 of dorsal shortened as in Skiffia lerma; pectoral 1 X in head ; ventral 2 ; 

 alimentary canal coiled on right side, its length 3^3 times total length 

 of the fish; peritoneum black; gill rakers long and rather stout; 20 on 

 the first gill arch; vertebras i6-(-i8=34. 



Color of female light olivaceous; a dark spot on hinder margin of 

 each scale on upper half of body, forming lines along the rows of scales 

 much as in species of Mollienesia; a prominent black bar at base of 

 caudal fin; male nearly uniform in color, with the anal and dorsal fins 

 black, margined with yellow; black caudal bar indistinct. Length 

 about 2}4 inches. 



This species reaches a length of 2.50 inches, and is known only 

 from the Lerma basin, near Ocotlan. The young are born during the 

 latter half of May. 



132. Skiffia lermae Meek. 



Skiffia lerma Meek, Field Col. Mus. Pub. 65, 1902, 102; Celaya; 

 Patzcuaro. 



Basin of the Rio Lerma. 



Head 4; depth 2^ to 3^; D. 13; A. 14; scales 14-37- Bod y deep, 

 much compressed; head small; snout pointed, 4 in head; mouth small, 

 the lower jaw the longer; eye large, 3 in head; interorbital slightly con- 

 vex, its width 2% in head; dorsal fin slightly in advance of anal, mid- 

 way between base of caudal and posterior margin of the orbit ; base of 

 dorsal 2 in head, its height in females \]/ 2 , slightly higher in the males; 

 pectoral xy$ in head; ventrals 2 in head; gill rakers stout, 20 on the 

 first arch; alimentary canal coiled on right side, its length 3% times 

 the total length of the body; peritoneum black; vertebras 16 + 18 =34. 



Color of females light olivaceous above, much mottled with darker, 

 nearly plain on lower half of the body ; young with a few faint brownish 

 bars on lower half of caudal peduncle ; a narrow dark lateral band and 

 a prominent black bar at base of caudal ; the color of the males nearly 

 uniform dark-olivaceous, the anterior half of some specimens being 

 nearly black ; the black caudal bar much less conspicuous than on the 

 females ; a dark line on the under side of the caudal peduncle in both 

 sexes. Length about 2.50 inches. 



