IO6 VICTOR E. SHELFORD. 



with similar integuments. Of the amphibians, the Plethodons 

 died in dry air in 58 min. (cinereus} and 87 minutes (glutinosus} 

 and are rated respectively at - 72 and - 85; Bufo died in 160 

 minutes and is rated at - 32 (compare charts I. and II.). Of 

 the chitin-covered animals Pterostichus (Chart V.) is rated at 



- 72 (single experiment) and died in 1,300 minutes; Fontaria at 



- 60 died in 1,830 minutes; Geolycosa rated at + 15 died in 

 2,200 minutes (compare charts III. and IV.). 



The ratings given in Table VIII. clearly fall into two groups 

 which are habitat groups. The Plethodons, Fontaria and 

 Pterostichus were taken from the surface of the ground under the 

 leaves and in a primeval beech forest; Geolycosa and Microbembex 

 ( + 6, see Chart V.) are regular residents of the driest open sand 

 areas. The toad is an incidental resident of the sand area. A 

 comparison of Tables VII. and VIII., shows that while a relation 

 exists between habitat and survival time it is confined to animals 

 with similar integuments. No such relation exists when one 

 entire habitat is compared with the other habitat group. Omit- 

 ting the toad, we find that the regular breeding residents of the 

 two habitats (beech woods and open dunes) differ in sign and 

 degree of reaction in a manner comparable with the difference 

 in physical conditions of the habitats (Shelf ord, ! I2&). Distri- 

 bution is then not a life and death matter for adults but a matter 

 of behavior reaction (Shelf ord, 'n, 'i2a, '126; Shelf ord and Alice, 

 'i2a, 'i2b). 



A further comparison of the different species given in the 

 table shows important relations to vertical conditions of forest 

 developmental stages (Yapp, '09; Sherff, '12; Shelford, 'i2a; 

 Fuller, '12). The wood-frog spends much of its time during the 

 day hopping about the forest floor. P. cinereus lives more of the 

 time beneath the leaves and is clearly more sensitive to evapora- 

 tion. P. glutinosus occurs in the beech woods proper in numbers 

 only in moist seasons; ordinarily it is confined in ravines where 

 Fuller ('12) found the average evaporation per day for the season 

 to be 1.5 c.c. less than at the surface of the forest proper. Since 

 glutinosus occurs in moister situations than does cinereus, the dif- 

 erence in the sensitiveness of the two species is related to habitat. 

 The habits of Pterostichus are not well known ; the species studied 



