1914.] NATURAL SCIENCES OF PHILADELPHIA. 471 



each of which is separated from the next succeeding one by a low 

 escarpment or terrace. The youngest of these is practically on a 

 level with the river and forms a strip of marshland varying in width 

 from a fraction of a mile to three or four miles. The most typical 

 representative of this level is the well-known Tinicum Marshes 

 immediately south of Philadelphia. In physiographic and floristic 

 features these marshes bear a close resemblance to the undrained, 

 open bottomlands of the Central States. Except where ditched 

 and diked, these marshes are permanently covered with water backed 

 up by the tide. They support a luxuriant growth of hydrophytic 

 grisses and sedges. The soil is a rich, dark muck, the dark color 

 being due to the decay of the marsh vegetation. 



Back of these river marshes is a terrace, about forty feet in height, 

 which marks the border of a level tract corresponding to an earlier 

 stage of deposition (Cape May Stage). A still earlier stage is repre- 

 sented by a second terrace a mile or two further away from the river 

 (Pensauken Stage). This extends back to the escarpment that 

 marks the position of the fall-line. The deposits forming these 

 terraces are alluvial in origin and consist of light-colored gravels and 

 clay loams essentially similar in appearance and texture to the 

 typical Piedmont soils. The soil is quite fertile and is extensively 

 cultivated, so that the region consists mostly of open fields and 

 pastures. 



The Orthoptera of these upland terraces are, with two exceptions, 

 common Piedmont types, so that from the standpoint of their grass- 

 hopper fauna these terraces are a part of the Piedmont. The two 

 exceptions are Orphulella pelidna and Melanoplus differentialis, the 

 former of which I have found to be locally quite frequent along the 

 edge of the lower terrace, as at Bartram's Gardens, but it is not 

 quite as common or as evenly distributed as its congener, 0. speciosa, 

 which is a typical Piedmont species. Melanoplus differetitialis is in 

 a class by itself. It appears to have been introduced from the West. 

 It is now abundant in the low lands bordering the Delaware River 

 and frequently migrates from them to the neighboring uplands. 



One Piedmont species has never, so far as I am aware, been recorded 

 from these terraces. I refer to Hippiscus tuberculatus. 



In the following list I give the species of grasshoppers, which, so 

 far as known, occur on these terrace lands: 



Dichromorpha viridis Arphia sulphur ea 



Orphulella speciosa " xanthoptera 



" pelidna Chortophaga viridifasciata 



