18 PROCEEDINGS OF THE 



coastal plain as compared with the uplands, probably due to the 

 presence of considerable areas of woodland and marshland which 

 offer greater facilities for obtaining food. 



From what evidence has been gathered it appears that such 

 typically Carolinian birds as the Blue- Winged, Worm-Eating, 

 and Kentucky Warblers, the Acadian Flycatcher, the Carolina 

 Wren, Tufted Titmouse and Carolina Chickadee, the Cardinal, 

 the Chat and the Turkey Buzzard, all of which represent the 

 more northerly element of what might properly be termed a 

 Coastal-Plain Fauna, are in reality much more abundant in the 

 coastal-plain tracts of southeastern Pennsylvania than in the 

 upland districts ; that the history of the region indicates a 

 geologically recent invasion of a certain forest-type with its as- 

 sociate fauna along the coastal-plain border, and that this 

 border lies against an ancient slope of crystalline rock-forma- 

 tion known as the fall-line or upland terrace which separates 

 two very distinct topographic areas, a Piedmont land of great 

 antiquity and a recently elevated strip of coastal sea-bottom. 

 That a fauna does not represent a fixed state of things is evi- 

 dent from the numerous instances of the invasion of these types 

 northward into localities that have become suitable as habitats. 

 That temperature does not exert a controlling influence in this 

 instance I think must be admitted. It is a question of difference 

 of soil and of vegetation as conditioned by soil, and soils are a 

 part of those ultimate geological processes, the influences of 

 which are for ever working out the story of a long inheritance. 



