THE CYPRINODONTS. 149 



Orestias elegans sp. n. 



B. 5; D. 15; A. 16; P. 16-18; LI. 34-36; Vert. 14+18. 



Compared with that of 0. Agassizii the body is more elongate and less 

 compressed, the crown between the eyes is more convex, and the eyes are 

 smaller. Head three and three fourths, and height four times in the length 

 to the caudal. Eye as long as the snout, four fifteenths as long as the head, 

 as wide as the interorbital space. Mouth vertical, cleft not reaching the level 

 of the lower edge of the orbit. Teeth in a single series. Dorsal originating 

 midway from eye to caudal and distant the length of its base from the latter. 

 On the male anal and dorsal, toward their extremities, are laterally beset 

 with small sharp spines. Caudal about four-fifths as long as the head, con- 

 vex on its posterior margin. In a female of two and one-eighth inches the 

 eggs are nearly mature. Scales medium, flat, so thin as to be hardly visible, 

 apparently lost at each side of the vertebral series. 



Light brownish, yellow tinted, lower half silvery, top of head dark ; a 

 silvery band along the side, in cases longitudinally bisected by a dark streak ; 

 thickly freckled with small spots of brown ; larger blotches on the dorsum, 

 becoming more distinct and vertically elongate at each side of the dorsal fin 

 and above the caudal pedicel ; five or six narrow wavy transverse streaks of 

 brown on the caudal fin, and two or three similar ones on the dorsal. This is 

 at present the smallest known species of the genus. It was taken in small 

 lakes among the head waters of the Rimac river, Peru : " Lagunas de la Cor- 

 dillera de la Ascension, origen del rio de Santa Eulalia que se reune con el 

 rio Rimac que pasa por Lima, 4200 metros." 



Orestias Mtilleri. 



Orestias Mullen Val., 1S46, C. V. Poiss., XVIU, 240; Blkr, 1S60, Cypr., 487 ; Garm., 1876, Bull. 

 M. C. Z., Ill, 276. 



Orestias luteus Gthr., 1866, Cat., VI, 331. 



B. 5; D. 12-13- A. 13-14; P. 17-19; LI. 38-42; Ltr. 16-17; Vert. 

 14 + 18. 



Body moderately compressed ; back not high, but arching regularly from 

 head to dorsal ; caudal section compressed, slender, deepening considerably 

 at base of caudal fin. Head large, as broad as high, one third of the length 

 to base of caudal, crown flattened, orbits prominent above. Snout shorter 

 than eye, broad, blunt, rounded, not bent upward as in 0. Cuvieri. Mouth 



