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THE AMERICAN NATURALIST [Vol. XLI 



of the vole, rejected parts of its food. Microtus nests are commonly 

 made of the husks, leaves, and silk of the corn, or of the chaff 

 and leaves of the wheat which it devours. It is easy to conceive 

 that in this way the nesting habit of the shrews also originated. 

 If this be true, the use of grass, leaves, and sedge, now so common 

 among the shrews, must be a secondary modification, since these 

 articles are not rejected food materials. 



The fact that in the laboratory the shrew did not make any 

 defined runs at the surface, suggests that it may not make any in 

 the field. If this is true, the runs which it occupies were probably 

 made by IMicrotus. They may have been entered in pursuit of 

 game, and when the original owners were captured, their burrows 

 were appropriated. The finding of broken snail shells in Microtus 

 nests seems to support this view, since Microtus does not eat snails. 

 The shells must have been carried thither on a foraging expedition, 

 and devoured in the nest of the vole. To what extent the runs used 

 by Blarina have been appropriated by it has not been determined. 



Many of the shells found around the nests of Blarina, in under- 

 ground chambers, and in the burrows, were shown by the numbers 

 painted upon them to be those which were previously heaped at 

 the surface. The snails, therefore, were being hoarded, and 

 used gradually. Bachman (1837, p. 370) mentions that beetles 

 are hoarded by shrews of the genus Sorex, and Merriam (1886, p. 

 169) thinks it probable that Blarina stores food. Dahl (1891) 

 has found masses of earthworms, having their anterior segments 

 injured, in tlie burrows of the European mole; but Adams (1903, 

 p. 14) thinks they merely fell in and could not get out,— he does 

 not explain the injur}' of the anterior segments. There is no 

 mention of hoarding among shrews on as large a scale as this of the 

 snails seems to be. It has been noted that the snails were carried 

 out on top of the ground in considerable numbers when the 

 temperature fell markedly, and were taken l)ack in equally 

 large numbers wlien there wa^ a iii;ukc<] ri^c in temperature. 

 The snails seem to be kept in the coUk-st [.lace avaikable. In 

 cold weather this is above ground; in wartn wciirhcr, in the bur- 



