XV A PLAGUE OF VOLES 477 



They have, in the case of the first three, transverse ridges, from 

 which stand up two sharp and long tubercles. The other teeth 

 have two ridges. The incisors are pale yellow. The shape of 

 the teeth and the smallness of the caecum suggest that this 

 Eodent is not so purely a vegetarian as others, and that it 

 nourishes itself largely upon insects. 



Sub-Fam. 8. Microtinae. — The A'oles or AYater-Eats form a 

 distinct group of Murine animals, to which the sub -family 

 name of Alicrotinae has been applied from the genus Microtus 

 (more generally known as Arvicola), a genus which includes 

 the Water-Eat and Field- Voles of this country. This genus 

 has short ears, and a short and hairy tail. Its build is 

 stouter and clumsier than that of the Eats. The genus is 

 confined to the Palaearctic and the Nearctic regions. In this 

 country there are three species. The best known is the AVater- 

 Vole or Water-Eat, M. amphibius, which has been seen by 

 most people, and which frequents streams, p)onds, and canals. 

 The feet, curiously enough, are not webbed, which seems to 

 argue the recent adoption of an aquatic life. Mr. Trevor- 

 Battye has remarked that this animal, when swimming at 

 leisure, uses its hind-limbs only, carrying tlie fore pair at 

 the sides like a Seal. The Bank-A'ole, M. glareohts, is rather a 

 local species in this country. It is a terrestrial Vole, and 

 burrows. The Field- Vole, M. agrestis, has become notorious on 

 account of the "plagues," to which its immense numbers have 

 on occasions given rise. It is the smallest species, and has a 

 greyish-brown fur like the Water- Vole, the Bank-A'ole being 

 redder. To give an idea of the cost of the depredations of this 

 animal, Mr. Scherren quotes ^ a farmer who gave evidence before 

 the Agricultural Commission to the effect that, putting the 

 damage of one Vole at two pence, the amount of loss suffered on 

 a farm of 6500 acres in two years would be £50,000 ! 



The genus Fiber comes very near the last. It is a North 

 American genus. The hind-feet are slightly webbed ; the tail is 

 a trifle shorter than the body, and is compressed and scaly, with 

 scattered hairs. The thumb is short, but with a fully-developed 

 claw. As in the last genus, the small and large intestines are 

 roughly of the same length, and the caecum is about one-fourth 

 of the length of either. It is known as the " Musquash." 



' Popular Natural History of Animals, London, 1898. 



