36 



STUDIES IN AMERICAN TETTIGONIIDAE (oRTHOPTERA) 



marked or represented by mere nodes in individuals of the same 

 species. Instead of being a character of prime importance, 

 which has been used for the separation of genera groups, in the 

 Decticinae the degree of development of these spines can not 

 be used as a basic character, as we now know it is valueless as 

 even a specific criterion in Atlanticus and, as Caudell has shown, 

 in Eremopedes. 



Our study makes it evident that the species of the genus 

 fall quite naturally into four groups, our ideas of the general 

 relationship of which, and of the component species, are as 



follows: 



, — ^ '- testaceus 



Group A 



-pachymerus 



-davisi 



" monticola 



Group B 



-americanus 



Group C 



-gibbosus 



Group D 



-dorsalis 

 glaber 



-calcaratus 



These groups may be in general characterized as follows : 



Grottp a 



testaceus 

 pachymerus 

 davisi 

 monticola 



Size medium to small. Pronotal disk 

 with sharp lateral angles; disk proper dis- 

 tinctly constricted on cephalic third to 

 fourth. Tegmina of male always with 

 distal section not covered by the pro- 

 notum. Cerci of male moderately ro- 

 bust, with a distinct but short, approx- 

 imately median, tooth. Subgenital i)late 

 of male angularly or arcuately emargi- 

 nate, but never fissate. Subgenital plate 

 of female moderately but never very 

 deeply divided; lateral sections arcuate, 

 obtuse-angulate or rectangular distad. 

 Spurs of caudal tibiae normal. 



