ANNOTATED LIST OF THE SPECIES 365 
wider at the opercle (1.4 compared with 1.6); head 3.0 in the length, as wide as 
long and equal to greatest depth of the body; eye smaller (4.6 as against 4.2), 
slightly oval, equal to snout (while in luteus of this size the eye exceeds the snout); 
eye in the interorbital width 1.7—2.0 as compared to 1.3. The mouth in these 
specimens is, as the authors state, vertical, wider than in luteus, the gape equal to 
the interorbital width; teeth much fewer, and in a single series, compared with a 
double rank in luteus. Opercle of about equal extent, but ending in a much less 
acute angle. Caudal peduncle shorter, squarely truncate rather than expanded 
at the base of the fin. 
Preorbital scaled; cheek scales reaching to the anterior vertical from the eye, 
or nearly so; three vertebral series rather regular, 12 scales in middle series; granula- 
tions of anterior scales beginning to appear. 
Numerous clumps of chromatophores falling into 2-3 longitudinal rows, form- 
ing a reticulate pattern. Dorsal and caudal fins from nearly hyaline to several 
broken rows of fine punctulations, very few on anal and pectoral. Head and 
shoulder scales darker about margins, with lighter centers. 
Turning to the bay of Huancané, we find a series of smaller specimens, some 
of which are more slender, and may be luteus. In this age range the scales are more 
deciduous, the vertebral series more regular, 12-14, only the largest beginning to 
show any granulation of scales, the opercle often showing silvery through the 
still-thin scales. Colors similar. O. luteus of this size more arched on the nape, 
less robust, with more tapering caudal peduncle, lateral angle more acute, mouth 
more vertical and more deeply cleft, eye more elevated, larger, 4.3 in the head; 
crown flatter, overhanging the larger eye; snout shorter, 0.5 times the eye; more 
granulations begun on the enlarged scales; finrays all separated by a dark mem- 
brane; reticulated patches wanting. 
16080, 4, 97-120 mm., Puno, Allen, November, 1918. 
Separable from nearby O. luteus by the extreme breadth of the opercle, the 
pointed head, small, narrow much upturned mouth with fleshy lips, pointed snout, 
often greater convexity of the predorsal arch; shorter body, abruptly compressed. 
The chunkiest of all the species, with the most pointed head, the contours of a 
plummet. 
Postorbital portion of the head 1.4-1.7 greater than the anterior moiety (end 
of snout to posterior border of orbit); opercle acutely angular; body becoming com- 
pressed rapidly from opercle to anus; caudal peduncle deep (but less so than OQ. 
luteus), its depth nearly equal to the postorbital portion of the head, shorter than 
the peduncle of luteus, widening less at the base of the caudal. 
Mouth usually described as larger than that of lutews. This should be inter- 
preted as meaning wider, but with the gape crescentic and not curved sharply 
downward into a horseshoe. Except possibly for O. olivaceus, the most superior 
mouth of all Orestias species; thick-lipped, almost without teeth, as described by 
Valenciennes. 
These specimens may at least be reconciled with the much smaller ones above, 
