1914.] NATURAL SCIENCES OF PHILADELPHIA. 451 



xerophilous, mesophilous and hygrophilous. The xerophilous society 

 is characteristic of relatively dry situations. Morse^^ recognizes 

 three subdivisions or associations of this group, i.e., saxicolous or 

 rock-frequenting, arenicolous or sand-frequenting and humicolous 

 or those frequenting soils, loams especially, which although dry, 

 contain a larger percentage of moisture than the sands. The last 

 association naturally merges into the typical mesophilous society. 

 In the Piedmont only the humicolous association appears to be 

 represented and this is naturally not always easily separable from 

 the dominant mesophilous society. 



The xerophilous faunule is typically developed in the Piedmont 

 upon the so-called "poor soils." These soils occur on uplands and 

 steep hillsides where, owing to rain wash, the soil is either thin or 

 stony and therefore capable of supporting only a coarse type of 

 vegetation. In some cases the dryness of the ground is due to the 

 texture of soil and underljdng rock which allows a relatively rapid 

 percolation of water, as on the ridges formed by the Chickies quartzite 

 and Stockton conglomerates, or to the chemical character of the soil, 

 as on the Conowingo or Serpentine Barrens. Where the woodlands 

 have been removed the vegetation on these areas is of a somewhat 

 open character, numerous bare patches of soil showing between the 

 more or less scattered plants. The dominant plant growth consists 

 of coarse herbaceous types, such as are typical of dry, waste land 

 (bunch-grasses, Andropogon spp., Panicum, etc., cinquefoU, sheep 

 sorrel, Rumex acetosella, blackberry and wild rose bushes). In such 

 surroundings we normally encounter the following species of grass- 

 hoppers : 



Orphulella speciosa Dissosteira Carolina 



Arphia sulphur ea Melanoplus atlanis 



" xantJioptera " femur-ruhrum 



Chortophaga viridifasciata " minor 



Encoptolophus sordidus ^' femoratus 



Hippiscus tuberculatus Xiphidium strictum 



" rugosus 



Other species of more sporadic occurrence, but typical xerophiles, 

 are Eritettix carinatus, Pseudopomala hrachyptera, and Orphulella 

 pelidna. 



Of the above species I would tentatively consider the following as 

 the more distinctively xerophilous: Orphulella speciosa, Arphia 



11 Researches on North American Acridiidae, Carnegie Inst, of Washington, 

 Pubhcation No. IS, 1904, p. 14. 



30 



