136 THE ZOOLOGIST. 



congeners. But there are three objections which in the opinion 

 of the Committee render this method almost worthless, except 

 for employment in houses, gardens, enclosed fields, or other 

 limited areas : — 



(1). It is very expensive ; the virus supplied to the Greek Government 

 was paid for at the rate of about 4s. a tube, containing enough when dissolved 

 to treat about two imperial acres — a cost which in many instances would 

 exceed the rent of the Scottish hill-pasture. To this must be added the 

 price of bread used in distributing the virus, which would appreciably raise 

 the cost of the process. Thus to deal effectually with a hill-farm of (say) 

 6000 acres, would entail an expenditure of from £700 to £1000, making 

 the remedy more costly than the evil. 



(2). Mouse-typhus is not contagious ; it can only be communicated to 

 those animals that will swallow some of the virus. The allegation that 

 healthy voles will become infected by devouring the bodies of the dead has 

 not been satisfactorily proved. That Greek voles when in captivity have 

 been observed to feed upon the corpses of their fellows hardly warrants the 

 assumption that Scottish voles in a state of liberty will do the same ; and 

 unless the disease were communicable from one animal to the other, it is 

 not easy to see how the remedy could prove effective on extensive hill- 

 pastures. 



(3). The fluid loses its value in about eight days after preparation. 

 Consequently much disappointment might ensue if, after a supply had 

 been obtained, a fall of snow or wet weather were to interfere with its 

 distribution over the land. 



The remedy which has been found most effectual in Thessaly 

 is an injection of the fumes of bisulphide of carbon into the 

 burrows. This, however, is a more expensive process than the 

 other, besides being injurious to the health of those engaged in 

 its application. It is, moreover, inapplicable to the Scottish 

 vole (Arvicola agrestis), which does not burrow to a depth like 

 the vole of Thessaly (Arvicola Gilniheri), but lives in shallow 

 runs amongst the roots of herbage. 



With the under-noted exceptions, the natural enemies of the 



voles may be divided into two classes, viz., those which destroy 



the voles and are harmless to sheep, crops, and game ; and those 



which, through preying on voles, are so hurtful in other ways as 



to have no claim to preservation : — 



(i.) Vole-killers, harmless or nearly so, (ii.) Vole-killers, hurtful in other 

 to sheep, crops, and game. ways. 



Owls of all sorts, Foxes, 



Buzzards, Ravens, 



Kestrels, Carrion and Hooded Crows, 



and the smaller Sea-Gulls. Great Black-backed Gull, 



and Adders. 



