318 TfitE ZOOLOGIST. 



troop from the slopes of the hills and the fallow-lands to the 

 cultivated fields. It was frequently observed that they followed 

 regular paths during their inroads. Thus they advanced along 

 the railway embankment; their progress seemed to be rather 

 slow. Perhaps they do not advance further till the inhabitants 

 of one of their strongholds or so-called castle {Burg) have become 

 too numerous. The " runs " which they excavate are at a depth 

 of about twenty to forty centimetres below the surface of the 

 ground. The extent of these " runs" varies, and we found them 

 extending in length from thirty to forty metres and more. 

 These "runs" are connected with the surface by vertical holes of 

 about five centimetres in diameter. In many places four, five, 

 and more holes led to the same " run." In such cases there is 

 generally not far off an enlargement for the nest, lined with 

 finely-gnawed vegetable material, where the young are produced 

 and reared. In front of newly-opened holes, the earth, which 

 has been thrown far out, forms smooth hillocks. There were 

 many well-defined and well-trodden paths on the ground, by 

 which the voles pass from one hole to another. They are never 

 seen out of their holes by day, not even in places where the 

 entire ground is riddled with holes like a sieve. They do not 

 come out in search of food till evening ; even then not many are 

 to be seen, but the peculiar squeaking noise they make is heard 

 everywhere. Next day all sorts of freshly -severed fragments of 

 plants are found in the holes. Stalks of corn they manipulate by 

 standing on their hind legs, and gnawing through the stalk ; 

 when this is bitten off they drag it into their holes to devour it 

 there, and sometimes make it smaller. They are extremely 

 prolific. Beginning in March, the female produces from six to 

 twelve young ones every month. A reliable observer informed 

 me that he had counted twenty-one foetuses in the uterus of a 

 pregnant female. The danger to the fields consequently increases 

 every month. The number of voles noticed this spring was 

 apparently as large as in 1866. At that time also they were 

 first noticed in the fallow-fields ; but, as the present mischief 

 done to the fallow-fields was but slight, the voles attracted no 

 particular attention, and no measures were taken for their de- 

 struction. But when the vertical rays of the sun dried up the 

 fallow-fields at the end of May, 1891, as happens every year, the 

 mice invaded the cultivated fields, in which alone they could find 





