FISH FAUNA OF LAKES OF SOUTHEASTERN OREGON. 87 
Rutilus oregonensis, new species. 
This name is here applied to a distinct form found in the isolated lake basins of southeastern Oregon. 
It is very similar to closely related forms found in the Sacramento, Klamath, and Columbia systems, but 
differs widely from R. olivaceus of the Lahontan system in important dental characters, the latter species 
having the pharyngeal teeth 5-5. 
It differs from the more nearly related forms as follows: From R. thalassinus in having shorter fins, 
a greater number of scales in the lateral line, in the series before dorsal fin, and above lateral line, and 
also in usually having one less dorsal ray; from R. bicolor in having generally a larger head, smaller 
scales, there being a greater number in the lateral series, between occiput and dorsal fin and above the 
lateral line; from R. colwmbianus in having smaller scales and in other minor points. These differences 
are shown in greater detail in the tabulated comparisons of the four forms, page 94 et seq. 
Description of type no. 55596, U. S. National Museum, from XL Spring, Abert Lake, Oregon: 
Total length 202 mm. Head 3.6 in length to base of caudal; depth 3.6; depth caudal peduncle 9; depth 
head at occiput 5; length snout 3.3 in head; maxillary 3.7; diameter eye 6.1; width space between eyes 3; 
height dorsal 1.8; anal 2.2; length pectoral 1.6; ventral 2; caudal 1.3; scales lateral line 52; above lateral 
line 13; between lateral line and origin of ventral 8; between occiput and origin of dorsal 27. 
Fic. 3.—Rutilus oregonensis, new species. Type. 
Body deep and heavy, the dorsal contour with an abrupt elevation at occiput. Mouth very oblique; 
maxillary extending to a perpendicular through nostril, not nearly reaching anterior border of orbit. 
Gillrakers on first arch 14, very short, not equal to half the diameter of pupil, acutely pointed. Teeth 
(from cotypes) 4-5, short and strong, a narrow grinding surface present, tips of smaller ones somewhat 
hooked. Peritoneum almost black. Intestinal canal very short, its length equal to about 1! times 
total length of fish. Lateral line complete, somewhat decurved immediately behind head. Dorsal 
placed directly above ventrals, the length of its base equal to height of third ray, the free edge straight. 
Anal shaped like the dorsal, length of base equal to height of fourth ray. Pectorals and ventrals bluntly 
rounded, the latter not reaching anal opening; notch of caudal broadly rounded. Color in spirits very 
dark, even the ventral surface being decidedly dusky; edges of scales being much darker than their 
centers. In life the color is dark olive, some examples having a greener tint, the fins with somewhat 
darker edges. 
Smaller examples do not have a prominent post-occipital hump, the elevation growing more pro- 
nounced with age. The young generally have the fins slightly longer and the caudal more acutely 
notched. In other localities the specimens are often lighter in color, the variation apparently coincid- 
ing with the immediate surroundings. In lighter-colored examples the peritoneum is also less dusky. 
Sexual differences are not striking, the males generally having slightly longer fins. Females appear 
to be much more abundant than males. 
