234 



MONOGRAPHS OF NORTH AMERICAN RODENTIA. 



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1* 



not noticeably if at all exceed those of the hind feet, and are of ordinary 

 arvicoline shape. The fingers have the usual relative lengths;* thumb 

 rudimentary, with abortive, fl.it, appressed nail ; third digit longest, fourth 

 scarcely shorter, second shorter, fifth much the shortest. The fore feet are 

 between S and i as long as the hinder, as usual; on top, furred moderately, 

 the longer terminal hairs reaching the ends of the claws but not concealing 

 them; under the fingers, naked and annulate; on the palm, naked, with the 

 following tuberculation: besides the pollical node, there is a tubercle just 

 antero-extcrnal of this, another at base of the fifth and second toes respect- 

 ively, and another at conjoined bases of third and fourth toes — five in all, count- 

 ing the pollical protuberance. The hind feet, likewise, show nothing notice- 

 ably different from Arvkola or Evotomys; speaking in generol terms, the 

 relative size is Ihe same, and so are the proportionate lengths of the digits. 

 The feet are hairy on top to the claws (the longest terminal hairs just 

 reaching the ends of the claws), and the soles are moderately furry on the 

 posterior third (as far as the back tubercle); perhaps a trifle pilose for ordi- 

 nary Arvicola, but showing nothing of the dense furriness, like a rabbit's, of 

 Myodea or Cuniculus. There are six plantar tubercles, as usual in ArvicolituB, 

 thus disposed : — one posterior, of moderate size, conical, not lengthened, 

 situate about half-way between heel and bases of middle iocs; a smaller one 

 close l)y, but a little further forward and more external; then one at btise of 

 inner toe — these three completing a triangle; one at base of second toe; one 

 at base of fifth toe ; one between bases of third and fourth toes. The toes, 

 as usual, are strongly annulate beneatli, with terminal smooth pad. The tail has 

 nearly the usual length, calibre, and hairiness of Arvicola, showing no approach 

 to the brevity and rabbit-like furring of Myodes or Cuniculus. Its length varies 

 in our specimens. In Baird's type, No. 1368, the only tail seen till now, this 

 member is noticeably longer than the hind foot, and distinctly bicolor ; in our 

 Oregon animal, No. 3798, it barely exceeds the hind foot, and is indistinctly 

 bicolor ; in the Kansas skins, it averages no longer than the hind foot, and is 

 almost unicolor. 



In color, both as to its pattern and its shade, and in gen^^.a! superficial 

 appearance, tliere is little to distinguish tills animal from Arvicola riparius, 

 for instance. Aside from the Oregon animal, which is in poor if not sickly 

 condition, and token in August, the pelage is beautifully fine, soft, and full, 



* Tbo right furo foot of No, 8G08 hIiowb a ciirious nbiiorinnlity ; the third digit being orrostod in 

 dovvlopniout, HO that it in no longer than the Ufth. The loft fore foot is normal. 



