128 MAMMALIA. 
This last country produces several small species of Hamsters, de- 
scribed by Pallas.* 
Arvicota, Lacep. 
The Campagnoles, like the rats, have always three grinders, but with- 
out roots, each one being formed of triangular prisms, placed alternately 
on two lines. They may be subdivided into several groups, viz.— 
Fiser, Cuv. 
The Ondatras or Field Rats, with semi-palmated hind feet, a long, 
scaly, and compressed tail, of which one species only is well known. 
F. vulgaris; Castor zibeticus, L.; Mus zibeticus, Gm.; Buff. X, 
i. (The Canadian Musk-Rat or Ondatra). As large as a rabbit, 
of a reddish-grey. In winter they construct, on the ice, a hut of 
earth, in which several of them reside together, passing through a 
hole in the bottom, for the roots of the acorus(a), on which they 
feed. When the frost shuts up this hole, the musk rats are under 
the necessity of eating one another. It is this habit of building 
which has induced some authors to refer the Ondatra to the genus 
Castor. The second subdivision is that of 
Arvicota, Cuv.—Hypupevs, Illig. 
Our common Field Rats, or ordinary Campagnoles, which have a hairy 
tail, about the length of the body, and without palmated feet. 
A. vulgaris; Mus amphibius, L.; Buff, VII, xliii. (The Water 
Rat). <A little larger than the common rat, of a deep greyish- 
brown; tail the length of the body. Inhabits the banks of rivers, 
and digs in marshy places in pursuit of roots; but it swims and 
dives badly (0). : 
A. terrestris; Mus terrestris, Lin. (The Schermaus, or Digger 
Rat of the Americans). Seems to differ from the Water Rat only 
in being somewhat smaller; its tail, also, is shorter. It lives under 
ground, like the mole, but especially in the meadows of high grounds. 
It excavates galleries, and transports the earth which it raises from 
its hole to some distance from the opening. Its magazines, which 
are principally filled with the roots of the wild carrot, cut into two- 
inch pieces, are frequently two feet in diameter. 
* M. aceedula.—M. arenarius.—M. pheeus.—M. songarus.—M. furunculus. See 
Pall. Glir. and Sch. 
{= (a) This is the plant called Sweet Flag, and was considered by Linnzus to 
be the only aromatic one which grew in the northern regions. Notwithstanding the 
certainty of Cuvier’s account, yet, it is laid down in Loudon’s elaborate work entitled 
the “ Encyclopzedia of Plants,” that no cattle whatever eat this plant——lHEne. Ep. 
(& (b) It would appear that the species called the Short-tailed Water-Rat is grega- 
rious, and that troops of them habitually migrate to places where suitable food may be 
obtained. ‘They have been known to be particularly partial to spots where the Equi- 
setum limosum (Smooth Horse-Tail) is abundant. How such large companies as 
have been frequently observed, can change their localities without being seen in their 
transits, is a mystery which still remains unsolyed.—Ene. Ep. 
