1915.] NATURAL SCIENCES OF PHILADELPHIA. 293 



THE GENUS GRYLLUS (ORTHOPTERA) AS FOUND IN AMERICA. 

 BY JAMES A. G. REHN AND MORGAN HEBARD. 



To the systematic orthopterlst, the crickets of the genus Gryllus 

 have proven to be one of the greatest stumbHng-blocks in the order. 

 This is true of the forms found in both hemispheres, but this assertion 

 has especial emphasis when the American forms alone are considered. 

 This is not due to a lack of study, as Scudder and Blatchley have in 

 recent years both endeavored to diagnose certain or all of at least the 

 North American species, using what might be called "conventional" 

 morphological characters, while Lutz, approaching the subject from 

 a biometric point of view, concludes that species in an anyway 

 natural sense do not exist in the genus, in this skepticism representing 

 the other extreme from Scudder, who categorically defines a number 

 of species. 



The present authors have been unable in the past to approach the 

 subject with sufficient material to enable them to do more than 

 endeavor to assign certain of their series to various of the forms 

 recognized by Scudder. There has been constant and increasing 

 difficulty in doing this, as, while some individuals would fit certain 

 of the specific descriptions, others would be found agreeing in various 

 features with two or more of the specific diagnoses, the sum total 

 of almost any representation showing an endless complexity of the 

 characters used to differentiate the numerous described forms. 



The fact is quickly recognizable that almost all of the descriptions 

 of these species were chiefly concerned with size, coloration (not 

 color pattern), venation (in number of transverse (oblique of Saussure) 

 veins in the male tegmen and number of branches of the mediastine 

 vein in both sexes), tegminal length, degree of development of wings 

 and ovipositor length. Such factors have been found to be of minor 

 importance or of no specific value whatsoever in certain other related 

 genera, and the natural uncertainty of the status of the American 

 forms has led us to undertake a more searching study of these. This 

 work is based on all of the American material of the genus before us, 

 1,504 specimens. The results explain to our complete satisfaction 

 the reasons for the past confusion, a summarj^ of which is given 

 below. 



