THE CYPRINODONTS. 149 
Orestias elegans sp. ». 
B. 5; D. 15; A. 16; P. 16-18; Ll. 34-36; Vert. 144+ 18. 
Compared with that of O. 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 Miulleri. 
Orestias Milleri Val., 1846, C. V. Poiss., XVII, 240; Blkr., 1860, Cypr., 487; Garm., 1876, Bull. 
M. C. Z., III, 276. 
Orestias luteus Gthr., 1866, Cat., VI, 331. 
B. 5; D. 12-13 A. 138-14; 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 O. Cuvieri. Mouth 
