MUUID^E— ARV1COLIN.E— ARVICOLA TOWNSENDI. 187 



of tail is one of the strongest features of the supposed species. The ears 

 appear to us rather larger every way in proportion. They are three-quarters of 

 an inch long and half an inch wide, and obviously project a little (about 0.10) 

 beyond the fur. This rather exceeds anything we have seen in the largest-eared 

 "edax'', and is positively beyond the limits of typical riparius, in which the 

 ear rarely if ever overtops the fur. The character of the soles is the same 

 as in riparius; there are six tubercles. The soles are very sparsely hairy, 

 and this only about half-way to the base of the nearest toes, but are fringed 

 with hairs their whole length, as usual. The fore feet, measured from the back 

 of the palmar callosity,* are a little less than half as long as the soles; from 

 the wrist, three-fifths of the hind foot. The relative lengths of tail and body 

 are. as 1.00 : 0.45 ; that is, the tail is somewhat less than one-half the head 

 and body. Its hairiness is on an average. The head is a little over one- 

 fourth as long as the head and body together, and a little less than one-third 

 the body alone. The whiskers are about as long as the head. 



In color, there is little to distinguish it from an average riparius. The 

 upper parts, however, are somewhat, paler or clearer, owing to greater pre- 

 dominance of (he yellowish-brown over the black. In the lighter-colored 

 specimens of riparius, the shade is generally produced by a prevalence of 

 bay rather than of this yellowish-brown of townsendii. The under parts are 

 clearer than is usual in riparius, and have a brownish wash from the sides, while 

 the middle line of the throat is nearly white; but these differences are barely 

 appreciable. In this, as in all the allied species, there is a curious seeming 

 difference in color, according to the position in which the specimen is viewed. 

 If held with the muzzle toward the eye of the observer, the general shade 

 is very dark, because the longer blackish hairs are chiefly seen ; if the skin 

 be turned the other way, so that these hairs are collectively foreshortened as 

 much as possible, the general effect is yellowish-brown. There are no 

 streaks or markings anywhere, except that sometimes the throat is quite 

 decidedly whitish ; in one specimen, in fact (No. 5026), there is a perfect 

 white streak along the throat; the whiskers are black and whitish ; the feet 

 brown. The tail is blackish-brown, and nearly unicolor; that is, the under 

 side is merely a little paler than the upper, and there is no dividing line. 

 The terminal pencil of hairs is, on the contrary, white, almost exactly as in 



* We take this measurement thus throughout this memoir. This explains an apparent discrep- 

 ancy hetween Build's and our measurements of the fore foot ; he taking it from the wrist-joint. His 

 length of fore foot averages 0.61, exactly as we should make out in the same way. 



