86 Miller Synopsis of the Voles of the Genus Phenacomys. 



Teeth. The teeth of Phenacomys longicaudus differ from those of the 

 other species in the reduction in width of the inner triangles of the upper 

 molars. This tendency is especially marked in the posterior inner tri 

 angles of the first and second teeth. In these the anterior face of the 

 prism is nearly parallel with the anterior side of the second external re 

 entrant angle. The anterior transverse loop of the posterior upper molar 

 is narrower than in other members of the genus and the terminal loop of 

 the same tooth is considerably shortened. In the lower jaw the enamel 

 pattern shows no characters beyond a general tendency to narrowness of 

 all loops and triangles. 



Measurements. Type specimen "(from skin): total length, 148; tail 

 vertebrae, 58; hind foot, 20.2" (True). Lane County specimen: total 

 length, 165; tail vertebrae, 63; hind foot, 20.8 (from fresh specimen by 

 the collector, A. Todd). 



General remarks. Phenacomys longicaudus differs so strikingly in propor 

 tions and color from all other members of the genus that it cannot be 

 compared with any. Its appearance is unique among the voles, though 

 faintly suggested by some of the Asiatic species of Alticola. 



BIBLIOGRAPHY OF THE GENUS PHEXACOMYS. 



1889. Merriam, C. Hart. Description of a New Genus (Phenacomys) and 



Four New Species of Arvicolinte. <North American Fauna, No. 2, 

 pp. 27-35, pi. ii-vii. October 30, 1889. Genus defined and four 

 species named, P. intermedius, P. celatus, P. lalimanns, and P. 

 ungava. 



1890. True, F. W. Description of a New Species of Mouse, Phenacomys 



longicaudus, from Oregon. <Proc. U. S. National Museum, xiii, 

 pp. 303, 304. Author's separates issued November 15, 1890. 



1891. Merriam, C. Hart. Results of a Biological Reconnoissance in South- 



central Idaho. <North American Fauna, No. 5, pp. 1-114. 

 July 30, 1891. Phenacomys orophilus described on pages 65, 66. 

 1891. Todd, Aurelius. An Oregon Mouse. < West American Scientist, 

 vii, pp. 240-242. September, 1891. Account of the arboreal 

 habits of Phenacomys longicaudus and copy of original descrip 

 tion of the species. 



1891. Flower, William H., and Lydekker, R. An Introduction to the 



Study of Mammals, Living and Extinct. Genus Phenacomys 

 mentioned on page 466. 



1892. Merriam, C. Hart. The Geographic Distribution of Life in North 



America with Special Reference to the Mammalia. <Proc. 

 Biological Soc. Washington, vii, pp. 1-64. April, 1892. List of 

 species of Phenacomys on page 25. Arvicola borealis Richardson 

 provisionally referred to this genus. 



1894. Nehring, A. [Review of North American Fauna, Nos. 1-5.] 

 <Naturwissenschaftliche Wochenschrift, Berlin, p. 346. July 

 15, 1894. Bones from cave in southern Hungary referred to the 

 genus Phenacomys. 



