1910.] NATURAL SCIENCES OF PHILADELPHIA. 401 



A REVISION OF THE NORTH AMERICAN SPECIES OF THE GENUS 

 ISCHNOPTERA (ORTHOPTERA). 



BY JAMES A. G. REHN and MORGAN HEBARD. 



Some months ago the study of a considerable series of specimens 

 of this genus from North Carolina furnished the incentive for a careful 

 examination of all the material on hand at that time, as well as a study 

 of the literature bearing on the genus as present within the limits of 

 the United States and Canada. The results were so interesting that 

 a number of appeals were made for additional material to enable us 

 to make our examination as complete as possible, and the cordial 

 responses placed in our hands for study an extensive and very valuable 

 series from the collections of the United States National Museum, the 

 Brooklyn Institute of Arts and Sciences, and the private collections 

 of Profs. Lawrence Brunei*, A. P. Morse and W. S. Blatchley, to all of 

 whom our hearty thanks are given for their cooperation. Primarily 

 this work rests upon the material in the collection of the junior author, 

 this representing about one-half of the five hundred and fifty-two 

 specimens examined. 



The two greatest difficulties encountered in studying the genus 

 were the lack of sex correlation on account of the usually great sexual 

 dimorphism, most of the females being considered species of other 

 genera, such as Temnopteryx and Loboptera (Kakerlac), and the confu- 

 sion or non-recognition of certain of the older species. In the present 

 paper every species of the genus known from within our limits has 

 the sexes correlated, with the result that Loboptera and Temnopteryx 

 are entirely eliminated from our fauna, with the exception of one 

 species of the latter genus known only from the female, the discovery 

 of the male of which probably will prove its membership in the genus 

 here treated. 



The extent of individual variation in species of the genus is consid- 

 erable, both in size and to a less extent in coloration. The length of 

 the tegmina is the most variable dimension, although its ratio to the 

 general size always remains much the same, only departing decidedly 

 in this particular in specimens which are really intermediate in 

 character between two geographic races. Coloration seldom varies 

 except along the lines of intensification and dilution, the cases of 



