MICHIGAN ACADEMY OF SCIENCE. 39 



The Maine Region, a fourth division, is considered under two heads: (1) 

 The Main Coast; (2) The Sphagnum Bogs. The state is rich in this latter 

 habitat which owes its origin to glacial ponds and lakes and so bears a per- 

 tinent relation to our discussion. The xerophytism of the coast is even 

 surpassed in these di'ained and undrained glacial ponds; a set of ecological 

 conditions are here operative which must have acted selectively upon forms 

 striving for occupancy when the belts of biota worked northward with glacial 

 recession. 



FLORAL ALLL\XCES. 



The table immediately follo'^ing will serve to evidence the occurrence of 

 the 118 arctic-alpine forms in these several regions defined. 



