1916.] NATURAL SCIENCES OF PHILADELPHIA. 103 



The zones may be briefly outlined as follows: 4 



Boreal or Canadian Zone. — This zone occupies the summits of the 

 higher mountains in North Carolina and Virginia, suck as the Black 

 Mountains, Koan Mountain, Grandfather Mountain, Mt. Pisgah, 

 Balsam Mountains, etc. This is the area of balsam forests within 

 the territory studied. We do not feel that the zone has been suf- 

 ficiently studied to consider the total number of species reported 

 from it as a fair index of the Orthoptera therein. 



Transition or Alleghanian Zone. — This zone comprises all the truly 

 mountainous country below the Boreal summits; in Georgia, how- 

 ever, being largely restricted to the elevations greater than 1,500 

 feet. Slope exposure is largely responsible for the presence or 

 absence of this element near its upper and lower margins. In North 

 Carolina, large valleys of tributary streams of the Tennessee carry 

 tongues of the Upper Austral for considerable distances into the 

 otherwise solidly Transition country. The same appears to be true 

 to a lesser degree in the Transition area of Georgia, which is in large 

 part much tinctured with Upper Austral elements. 



Upper Austral or Carolinian. — The area comprised in this zone 

 extends from the lower border of the Transition zoneTdown to a line 

 roughly drawn from a short distance up stream of the mouth of the 

 Potomac River, to Weldon, North Carolina, to Raleigh and Char- 

 lotte, North Carolina, traversing transversely the area between 

 Spartanburg and Columbia, South Carolina, and crossing the State 

 of Georgia- in a southwesterly direction to the vicinity of Warm 

 Springs, Georgia, then curving northwest into Alabama. As stated 

 above, pronounced valley intrusions of this fauna enter western 

 North Carolina from the Tennessee Valley, while in Georgia it 

 apparently pushes its way well into and even up the lower slopes 

 of the mountains, apparently in sharp competition with the 

 Transitions forms occurring in the same region. The two elements 

 will be governed in their distribution, at one of their points 

 of contact, by slope exposure; at another, by the normal cover or 

 by the burning-over of the land. As we have discussed above 

 under Physiography, a number of distinctly Lower Austral forms 

 occur within normally Upper Austral areas, at localities such as 

 Currahee Mountain, Toccoa, vicinity of Stone Mountain and Thomp- 

 son's Mills, and these extensions probably are, as suggested there, 

 due to the extending influence of large river valleys, which provide 



4 For a careful presentation of the life zones of North Carolina, see Brimley, 

 Journ. Elisha Mitchell Scient. Soc, XXIX, pp. 19 to 27, (1913). 



