128 . MAMMALIA. 



This last country produces several small species of Hamsters, de- 

 scribed by Pallas.* 



Arvicola, 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. — 



Fiber, Ciiv. 



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 («), 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 



Arvicola, Cuv. — Hypudjeus, 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 (6). 



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. accedula. — M. arenarius. — M. phoeus. — M. songarus. — M. funmculus. See 

 Pall. Glir. and Sch. 



f^ (a) This is the plant called Sweet Flag, and was considered by Linnasus 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 " Encyclopaedia of Plants," that no cattle whatever eat this plant. — Eng. Ed. 



^ (6) 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 maybe 

 obtained. They have been known to be particularly partial to spots where the Eqid- 

 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 unsolved. — Eng. Ed. 



