CHAPTER XVII. 



REMARKS UPON THE DISTRIBUTION OF ANIMALS AND PLANTS. 



.HE object of this chapter is to present a few additional facts re- 

 specting the distribution of animals and plants, and endeavor to 

 deduce from all that is known the precise boundaries between the Can- 

 adian and Alleghanian districts ; and to call the attention of botanists 

 to the importance of drawing the lines between the alpine and sub-alpine 

 floras. The determination of these questions requires the application 

 of a knowledge of our isothermal lines, both for summer and winter 

 temperature, the contour lines of elevation above the sea, and the 

 actual limits of the distribution of the principal animals and plants. 



The Distribution of Birds. 



From the writings of prominent ornithologists, it is now possible to 

 ascertain the geographical limits within which the different species of 

 birds rear their young. On account of their migratory habits, the birds 

 are reckoned to belong to those regions where they breed. Very many 

 arctic birds are seen within our limits, especially during the winter, but 

 these are not to be classed among New Hampshire birds. The lists 

 herewith appended are not exhaustive ; but I have taken pains to present 

 only those names which are stated to breed within our limits, by compe- 

 tent authorities. It will be quite desirable to collect facts respecting the 

 breeding of birds along the Connecticut-Merrimack water-shed, since 

 certain Canadian species may be found farther south along this line 

 than has been heretofore supposed. 



