430 
VERTEBRATA. 
tioii took place in Norway from the Circle of Umea to that of Lula, and that the winter accord- 
ingly was very severe in the former and miJd in the latter, though this was farther to the north. 
But if this be so, still the instinct only leads to destruction ; for even if they find a milder climate, 
as we have shown, they only go to their ruin. An instinct which leads a whole tribe of animals 
— millions in number, and at frequent intervals — through fatigue, wounds, privation, and anxiety, 
to premature and violent death, does not seem to be beneficent, and in its result, in this sense, is a 
direct contradiction of its motive. Such are not usually the ways of Providence. 
Pallas includes two other species of Lemming under the generic name of Myodes ; there are the 
M. lagurtis of Central Asia, and the parts of Europe nearest to it, and the M. torquatus of North- 
ern Russia. Nilsson names a species which he calls Lemmus semitricolor^ in the same division. 
There are several species of Lemming in North America, described by some naturalists un- 
der the generic name of Georychus. The Hudson's Bay Lemming, the Hare-tailed mouse of 
Hearne and Mus Hudsonius of Pallas, the Arvicola Hudsonia of Richardson, is five and a quarter 
inches long, the tail half an inch ; color, reddish-brown in summer and white in winter. In sum- 
mer it burrows in the ground, usually beneath stones and in dry ridges ; in winter it inhabits a 
nest of moss upon the ground, and seldom ventures abroad. It is an inoffensive creature, and on 
being captured becomes tame and gentle and as fond of being caressed as a kitten. It is a 
native of Sahara and the contiguous northern regions. 
THE TAWNX LEMMING. 
The Tawny Lemming, the Arvicola helvolus of Richardson, is smaller than the preceding, and 
resembles the Lapland Lemming. It is found about latitude 56° in mountainous districts of the 
northwestern British territories. 
Back's Lemming, Arvicola trimucronatus of Richardson, is five inches long, with a tail half an 
inch ; it is found near the Great Bear Lake. 
The Greenland Lemming, Mus Grmnlandicus of Richardson, is about six inches long, and is 
found in the polar regions of North America. 
Genus ARVICOLA : Arvicola. — This word is derived from the Latin arvum, " a field," and colo, 
"to inhabit," and embraces the numerous species of Field-Mice. It is equivalent to the term Cam- 
pagnol of Gervais and other French authors. The word Vole is popularly applied to many of the 
species, as Field- Vole,''^ " Water- Vole" &c. These animals are of small size, have a short tail, 
burrow in the earth, feed on grain, bulbous roots, and grasses, and neither climb trees nor become 
dormant in winter. They inhabit every quarter of the globe. About forty species are known, 
one-half of which are natives of North America. 
The Common European Field-Mouse, or Short-tailed Field-Mouse ; the Campagnol of 
Bnffon — A. arvalis — ^the Mus arvalis of Linnfeus, is of the size of the common mouse ; ears long, 
eyes prominent, tail one-quarter the length of the body, color a yellowish-fawn mixed with gray. 
It is subject, however, to varieties of color, some being black and others white, and others still a 
