288 



Wherever these are lacking the species is absent. In southern New Jersey 

 where sandy deposits are of practically universal occurrence Psinidia is 

 common, while on the opposite side of the Delaware River in Pennsylvania 

 it is unknown. A case like this shows us how essential it is that we should 

 have accurate local data before we can be certain of the exact range of a 

 species. 



The studies of Morse. Hancock. Rekn, Hebard, Yestal and others have 

 clearly shown the intimate relation betweeu the distribution of numerous 

 Orthoptera and certain features of the environment. As Shelf ord has so 

 well pointed out the success or failure of a species in any place will de- 

 pend on how closely the environmental complex approximates to that con- 

 dition at which the normal physiological activities of the species can be 

 carried on to the best advantage. Where this state of affairs obtains the 

 species will attain its maximum abundance ; if one or more of the factors 

 of the environmental complex are less favorable it will be present in 

 diminished numbers, while if any essential factor is prohibitive the species 

 will be absent. It is the aim of biogeography to explain the facts of or- 

 ganic distribution in terms of physiology, as an expression of the re- 

 actions of organisms to the varying conditions of their surroundings. In 

 the case of the Orthoptera this can be done only when we know much more 

 than we do now about the intrinsic qualities of the species and their 

 ability to accommodate their activities to varying intensities of environ- 

 mental factors. To acquire such knowledge will require much experi- 

 mental investigation. In the absence of such knowledge we must mean- 

 while be content to record the facts of distribution as actually observed 

 and to point out any correlation which may exist between the range of 

 species and the different types of environments. By the accumulation of 

 data along these lines a good foundation will be laid for the ultimate 

 causal interpretation of distribution and kindred biological problems. 



In the present article I have endeavored not only to give a full list 

 of the species observed about Lafayette, but in addition to point out the 

 more evident physical and botanical features of the region with which the 

 local distribution of the Orthoptera is correlated. Most of the facts here 

 given were gathered by myself, but I am also indebted for some valuable 

 additional data to Mr. P. W. Mason, Instructor in Entomology at Purdue 

 University, whose kindness in placing his notes at my disposal I here take 

 pleasure in acknowledging. 



