148 THE CYPRINODONTS. 
The shape of the head, massive snout, large mouth, numerous teeth, and 
larger scales readily distinguish this species from its nearest ally O. Pentlandii. 
Common in Lake Titicaca. 
Orestias Pentlandii. 
Orestias Pentlandii Val., 1839, L’Inst., VII, 118, —1846, C. V. Poiss., XVIII, 230, pl. 583; Blkr., 
1860, Ind. Cypr., 487; Gthr., 1866, Cat., VI, 329; Cope, 1875, Jour. Phil. Ac., 185; Garm., 1876, Bull. 
M. C. Z., III, 275; Eig. 1891, P. U. 8. Mus., XIV, 65,— 1894, Amn. N. Y. Ac., VII, 629. 
Orestias Bairdii Cope, 1875, J. Phil. Ac., 185; Hig., 1893, P. U. 8. Mus., XVI, 54. 
B. 5 (rarely 6); D. 13-15; A. 15-18; P. 19-20; Ll. 55-63; Ltr. 15-18; 
Vert. 16+ 21 or 17 + 20. 
Body elongate, moderately compressed ; caudal pedicel slender, broaden- 
ing at base of fin. Head one fourth of the length, without the caudal, broad 
and convex on the crown, narrowing toward the snout. Snout medium, little 
longer than the eye, rounded, blunt; chin vertical. Mouth medium, not 
reaching downward to the level of the lower edge of the orbit, nearly verti- 
cal. Teeth few, lacking the band of smaller ones behind the outer row, 
easily lost. Eye shorter than snout, two-elevenths of head, four-ninths of 
interorbital space. Origin of dorsal half way from occiput to caudal, little 
forward of that of anal, fin rounded above, forming an angle in the posterior 
rays. Pectorals moderately broad, reaching two fifths of the distance to the 
anal. Caudal three fifths the length of head, hinder margin slightly con- 
cave. Scales thin, somewhat deciduous, one to three vertebral rows larger, 
about twenty seven from head to dorsal, with age becoming thickened and 
rugose or smooth on head and shoulders and to some extent backward 
along the flanks, the hard enlarged series occasionally extending quite to the 
base of the tail. Belly naked, as also an area along the sides of the anal and 
behind it, or another at each side of the vertebral series of scales. 
Back brownish, sides lighter to silvery, in lower half, ventral surface 
white. Young mottled and blotched on the back. Dorsal and caudal brown- 
ish, with or without small spots of brown, that sometimes form transverse 
series. Fins in cases brownish toward the outer edges. Pectorals brownish 
in upper half, white in lower, Very common in Lake Titicaca. Specimens 
from the Cuzco Valley are about two thirds as large as those described ; they 
are much darker on the back, above the lateral line, and apparently belong 
to a distinct variety, fuscus. 
os 
