No. 488] 



HABITS OF Tin: Sinn-: 



changes are marked, the change in the number of shells is of the 

 same sign as the temperature change. Further, with the one 

 exception of ^lar. 6, all the considerable changes in the number of 

 shells occurred at times when the temperature changes were of 

 opposite sign. On this date there seemed to have been a marked 

 removal of shells into the burrows, while at the same time the 

 temperature had fallen. However, five days had elapsed since 

 the last preceding visit. In this time there had not been a steady 

 decline of the temperature; but the temperature had risen 8° 

 between Mar. 1 and Mar. 3, and then fallen 12° from Mar. 3 to 

 Mar. 6. Had I observed the shells on Mar. 3, the number of 

 shells might have been much smaller than for ^Far. 1, and then 

 increased to ^lar. 6. This seems especially probable since some 

 of the individual heaps showed an increase on Mar. 6, and others 

 a decrease. The decreasing effect of the rise of temperature 

 prevailed. 



Nests axd Burrows 



The Burrows. — Tlio record of the snails was closed Apr. 7. 

 Though a tVw occupied shells were still above ground, the weather 

 was then so warm that several of the snails were found crawling 

 about. Records of their transportation were untrustworthy after 

 that time, and were discontinued. By this time the frost was in 

 large measure out of the ground, and excavation of the burrows 

 was begun. Two methods were employed. AVhere the ground 

 was not very wet, flour was sometimes blmvn into tlic bunou s ^^ ith 

 a small hand bellows. The burrow Avas then ciuvfnlly opciicii as 

 far as the walls were whitened, and more flour was l,i.,un in. If 

 the ground were wet, the flour so-.n becamr uun^wuvA and lo.t 

 much of its whiteness. A more Mu.r^^f.il i.uMhn.l ua^ m ,,a^s a 

 rather stiff rubber tube into the burrow to keep it open whilf the 



