16 PROCEEDINGS OF THE 



Worm-eating, Blue-winged and Kentucky Warblers are very 

 rare in the New Jersey coastal plain but plentiful in the rich 

 wooded valleys of Pennsylvania. We have exactly similar 

 cases in plants, very rare or absent in New Jersey (close to the 

 Delaware if present) and common in the Susquehanna and 

 other valleys in Pennsylvania. These distributions are prob- 

 ably by character of country. ' ' 



Now by ' ' character of country "I take it that Mr. Stone 

 refers to just this condition of soil and vegetation influences that 

 we have been discussing. Referring to the second query ad- 

 vanced in this paper, that of the efficacy of the fall-line as 

 a faunal barrier, I must again quote Mr. Stone who has shown 

 in a recent work,^ the gist of which he gave me in a letter, that 

 the fall-line in New Jersey and Pennsylvania forms a very sharp 

 line of demarcation in plant life, the coastal-plain flora extend- 

 ing right up to its base, often crossing the Delaware River as at 

 Tinicum and in eastern Bucks County. Such trees as the 

 Sweet Gum (Liquidambar) and the Willow Oak (Quercus 

 phellos), typical of the coastal plain, apparently never cross the 

 "fall-line" in Pennsylvania. Mr. Stone finds a certain ele- 

 ment of the upland flora crossing the fall-line into western New 

 Jersey, especially along the Delaware, apparently taking posses- 

 sion of the richer soil, but the coastal-plain elements occurring 

 west of the fall-line are found only in isolated bogs or in local, 

 dry sandy areas. He is of the opinion that these are remnants of 

 an earlier flora, similar to the present coastal-plain flora, which 

 at one time covered the region above the fall-line and has been 

 superseded by the present, more advanced flora, elements of 

 which have come both from the North and the South, no doubt 

 coincident with climatic changes, forcing life toward and away 

 from the north polar region. 



If the Carolinian and Alleghanian (and other) life zones be 

 but relatively temporary conditions of a gradual shifting of 

 faunas, it would seem that the differences in present soil-condi- 

 tions on the two sides of the fall-line have made it a sharply 

 defined line in the case of plants, especially in Pennsylvania 



* Flora of Southern New Jersey. Annual Eeport N. J. State Museum for 

 1910, Trenton, 1912. 



