RODENTIA ARVICOLINAE ARVICOLA GAPPERI. 



521 



The skull bears a very close resemblance to that of Arvicola rutila, so close, indeed, that with 

 the limited materials at my command I am unable to indicate reliable characters to separate 

 specimens from Massachusetts and Lapland. 



This species exhibits a very close resemblance in many respects to Arvicola rutila of Pallas, 

 as shown by a comparison with specimens from Sweden and Kamtschatka. The size, general 

 shape, peculiar pattern of coloration, and characteristics of skull are nearly the same. Both have 

 the rufous back well defined against the lighter sides, the whitish feet and under parts. The ears, 

 however, in A. rutila are smaller and more densely covered with short hairs. The hind feet 

 are shorter, scarcely over .65 of an inch; the sole much more densely pilose from the heel, 

 beyond the first tubercles, or for more than half the length ; the hairs longer. The most con 

 spicuous distinctive feature, however, in addition to the shorter, more hairy soles, is the 

 shorter tail. The vertebral portion of this is shorter than the head, and not more than half as 

 long again as the hind foot ; it is very thick and does not taper till very near the end. It is 

 covered very densely with long, stiff appressed hairs, longer beneath and terminally than above 

 and at the base, and with a rounded pencil at the tip projecting more than one-third the length 

 of the vertebral portion. The American species, on the other hand, has the tail thinner, 

 longer than the head, nearly twice as long as the hind foot ; less densely coated with shorter 

 hairs, which are not appreciably longer in the posterior than the anterior half; the terminal 

 pencil in which is shorter. 



The species appears quite distinct from the Hypudaeus glareola of Keyserling and Blasius. 



The Arvicola gapperi was first described by Gapper in an article on the mammals of the dis 

 trict of Canada between York and Lake Simcoe. He supposed it to be the A. noveboracensis of 

 Bafinesque, but Dr. Bichardson having pronounced it undescribed, the editors of the Zoological 

 Journal called it after its discoverer. It has not hitherto been indicated as occurring within 

 the limits of the United States, though apparently not rare in eastern Massachusetts. 



I am very much inclined to consider the Arvicola fulva of Audubon and Bachman as identical 

 with this species. 



List of specimens. 



66 L 



Measured before skinning. 



