218 



NORTH AMERICAN FAUNA 



[No. 55 



sides rusty; lower parts creamy white with central area pale cinnamon or 

 russet. In worn pelage often pale yellowish brown. 



Measurements. Average of adults from type locality : Total length, 554 mm ; 

 tail, 253; foot 80. 



Distribution cmd habitat. Mainly the inland lakes and streams 

 of Nevada and the Great Basin generally. Specimens from south- 

 eastern Oregon have been referred to mergens, but are more or less 

 intermediate in characters and have been treated under osoyoosensis. 



FIBER ZIBETHICUS OCCIPITALIS ELLIOT 

 OREGON COAST MUSKRAT 



Fiber occipital^ Elliot, Field Columb. Mus., Zool. Ser. 3 : 162, 1903. 



Type. Collected at Florence, Oreg., by Edmund Heller, in 1901. 



General characters. About the size of F. z. osoyoosensis but slightly paler 

 and more reddish ; skull with narrower interpterygoid space. 



Measurements. Average of 4 specimens from type locality : Total length, 589 

 mm; tail, 271; foot, 83.5. 



Distribution cmd habitat. This seems to be a well-marked local 

 form occupying the Willamette Valley and a limited section of the 

 coast from Florence to Coquille (fig. 49). It inhabits the streams 

 and marshes of the more open country but not the streams of moun- 

 tain and forest. The animals are rather scarce, and very few speci- 

 mens have found their way into museum collections. 



Family CASTORIDAE: Beavers 

 CASTOR CANADENSIS PACIFICUS RHOADS 

 PACIFIC COAST BEAVER ; GANNOK of the Wasco 



Castor canadensis pacificus Rhoaids, Amer. Phil. Soc. Trans. 19 : 422, 1898. 



Type Collected at Lake Keechelus, Kittitas County, Wash., by Allan 

 Rupert, in 1893. 



General characters. Large, form heavy and compact (pi. 35) ; hind feet 

 large and fully webbed; tail broadly flattened, naked and scaly; ears and 

 eyes small; incisors large and chisellike; fur deep and soft, under cover of 

 long, coarse guard hairs. Fresh winter pelage, dark chestnut brown over 

 upper parts ; duller more sepia brown over lower parts ; cheeks yellowish brown. 

 Spring and summer pelage fades out to rusty or yellowish brown. Young about 

 the same color as adults. Skull large and long with heavy rostrum, long and 

 medium width nasals and heavy dentition. 



Measurements. Type specimen, adult female: Total length, 1,143 mm; tail, 

 330; foot, 185. A medium-sized male from Bear River, 12 miles east of 

 Woodruff, Wash.: Total length, 1,016 mm; tail, 280; foot, 185. Weight 43% 

 pounds. 



Distribution and habitat. These fine large beavers seem to occupy 

 the whole drainage of the lower Columbia River Basin and the 

 Snake River Valley (fig. 50). Specimens from the headwaters of 

 the Deschutes, La Grande, Pine Creek, near Pine in Baker County, 

 Oreg., from 5 miles south of Walla Walla, Wash., from Boise River 

 west of Boise, Idaho, are typical pacificus, while those from the 

 Owyhee River and Jordan Creek near Rome, in Malheur County, 

 are near pacificus in external characters but show skull characters 

 clearly grading toward the Nevada form. Specimens from western 

 Oregon in the Rogue River Valley, the McKenzie and Willamette 



