Arvicola. MAMMALIA. FERA. 23 



The dormouse is about the size of the common mouse, but fuller ; the tail 

 ia about 2 J inches in length, covered thickly with long hair. Eats its food 

 erect. During winter it subsists on the store of nuts which it had prepared 

 in autumn, and in very cold weather it becomes torpid. 



Gen. XXI. ARVICOLA. Vole.— No subsidiary incisors. 

 Roots of the grinders simple ; there are three on each side 

 on both jaws. Tail round and hairy, and about half the 

 length of the body. — The species of this genus differ from 

 the true mice, with which the older authors confounded 

 them, by the superior size of the head, the shortness of the 

 tail, and the coarseness of the fur. 



34. A. aquatica. Water Vole. — Body 7 inches long ; tail 3 

 inches. 



Mus aquaticus, Men'. Pin. p. 167 — Sibb. Scot. p. 12 — Mus amphibius, 

 Linn. Syst. i. p. 82 Water Hat, Penn. Brit. Zool. i. p. 1 18 — Mus am- 

 phibius, Walker's Essays, p. 490. W, Llygqden y dwfr ; G, Radan 



uisque Frequent in the banks of rivers. Not in the Northern Isles. 



The males are greyish-black on the back, the females yellowish-brown, with 

 scattered black hairs, both light coloured beneath. Tail covered with short 

 hair, and ending in a small pencil. This species swims and dives well. It 

 seems to feed exclusively on the roots of aquatic plants, no remains of the 

 bones of little fishes having been detected by us in its excrement, though 

 said to prey on such. During the winter months, it retires to a cavity formed 

 under ground in a dry bank, in which it has previously deposited a stock of 

 provisions. This consists in some cases of potatoes, as was observed by Mr 

 White, (Hist. Selb. i. p. 129.) ; and we have twice witnessed the same thing. 

 In the end of July we have found the stomach of a young one filled with 

 clover. It is probable that this species becomes torpid in the cold months. 



35. A. agrestis. Field Vole. — Body 3 inches and a half 

 long, tail 1^ inch. 



Mus agrestis, Ray, Quad. p. 218 — Short-tailed mouse, Penn. Brit. Zool. 

 i. p." 123. B, Llygoden gwlla'r maes. Vole-mouse in Orkney — In 



gardens and meadows, common. 

 This species never exceeds half the size of the former. The fur is browner 

 above and paler beneath, the ears are longer in proportion ; and the tusks, 

 which in the former are yellow, are in this nearly white. Doubts were en- 

 tertained by Linnaeus whether this and the former were distinct species. 

 But in his description of his Mas terrestris (our No. 35.), he introduces several of 

 the characters of the A. aquatica; and Pennant seems to have desciibed a young 

 one of that species for the agrestis. The field vole is most destructive in gar- 

 dens to seeds, especially to early peas, which, after germination has com- 

 menced, it scents out and digs up. The trap called by gardeners the Fourth 

 Figure catches them readily. It is equally destructive to young plantations, 

 and to coarse pastures. It multiplies prodigiously in certain seasons, and 



commits extensive ravages. 



In consequence of the progress of Society, one species has been extirpated 

 from the British Glires — the Beaver (Castor Fiber). This animal appears, 

 from the testimony of Giraldus de Barri, to have existed only in one river 

 in Wales and another in Scotland in the 12th century, (Hist. Camb. lib. ii. 



