274 Proceedings Port. Soc. JSfcit. Hist. 



Group II. Boeeal Plaxts, species which extend to 

 Labrador, Greenland and the Far ]S!^orth. 



Group III. Caxadiax-Alleghaxiax Plaxts, which 

 extend northward only to eastern Quebec or Newfound- 

 land and represent a transitional group between the 

 boreal species and the more southern forms. 



Group IV. Alleghaniax Plants, southern species 

 which reach their northern limit in eastern Maine or 

 adjacent ISTew Brunswick and Xova Scotia. 



Group V. Carolixiax Plaxts, which represent a 

 northward extension of the Atlantic Coastal Plain flora. 

 Group VI. Local Plax^ts, which are either species 

 with a limited range or isolated varieties of more widely 

 distributed species. 

 This grouping of the Penobscot Bay flora is a modifica- 

 tion of the classification of life zones of ISTorth America, 

 proposed by Dr. C. Hart Merriam.' In that part of eastern 

 Xorth America with which we are dealing Merriam recog- 

 nizes the following regions and life zones : 



Boreal Eegiox : comprising the northward part of the 

 continent with a narrow southward extension on the higher 

 mountains, 



1. Arctic-alpine zone — above the limit of tree growth. 



2. Hudsonian zone — the northern part of the conifer- 

 ous forest region which extends from Labrador to 

 Alaska and south in a strip on the higher mountains. 



3. Cmmdian zone — the southern part of this forest re- 

 gion, which comprises Canada, northern Xew Eng- 

 land and Xew York and a greater part of the 

 mountains. 



1. Merriam. Life Zones and Crop Zones of the United States, U. 

 S. Dept. Agr. Biol. Survey. Bull. 10. 1898. 



