REHN AND HEBARD 



159 



B. Caudal tibiae amied at distal extremity with three pairs of sj)urs. 



Conocephalus Thunberg 

 BB. Caudal tibiae armed at distal extremity with a single pair of spurs 

 (dorsal and ventral pairs absent. IVIale subgenital plate as in Xiphidion.) 



Anarthropus new subgenus 



The following diagram illustrates the relationship of the forms 

 here considered. 



-nllanli 



^fascial us fasciatus 

 "^ — fa scia tus v icin us 



s'pinosus 



'jrdcillim us 



hrevipen n is 



rcsacensis 



iicniorolii 



-occidental is 



-sirictui 



njgrnphilus 



stictotncrus 



-aigicdus 



nigroplcurum 



aUcn uatus 



niffrDphuroides 



-spartinae 



-saltans 



The numbers given above designate the three subgenera known 

 from North America; the letters indicate the natural groups of 

 the very large subgenus Xiphidion, each of which includes species 

 showing a greater or less degree of affinity, as given in the above 

 diagram. Of the species of group A, resacensis shows much the 

 greatest affinity to the species of group C. Group B is distinctive 

 and forms a decided unit, not a transition, between groups A and 

 C. Group C divides into two portions, the species forming the 

 first of these showing somewhat greater affinity to those of Group 

 A. 



In certain respects otherwise very different species show decided 

 similarity, thus allardi and nemorcdis both have unusually broad 

 tegmina with apices very broadly rounded and tympana of 

 males in proportion decidedly wider tlian is usual; brevipennis 



TRANS. AM. ENT. SOC, XLI. 



