REHN AND HEBARD 229 



vioiisly correctly recorded, we have examined and recorded in 

 the present paper 804 specimens, of which 571 are in the Hebard 

 Collection and that of the Academy of Natural Sciences of Phila- 

 delphia. The combined figures form a total of about 4700 

 American specimens of Conocephalus. 



We desire to express our deep obligation to Mr. A. X. CaudcU 

 of the United States National Museum, Dr. Samuel Henshaw of 

 the Museum of Comparative Zoology and Dr. F. E. Lutz of the 

 American Museum of Natural History, for the great privilege of 

 examining and studying all of the material of the genus contained 

 in the collections of those institutions. With the exception of 

 McNeill's exitiosum. and Bruners's two recently described species 

 we have had before us all of the types of the valid forms of the 

 genus located in America. 



Key to Males of the Species of the Genus Conocephalus found in 

 America north to the southern border of the United States.^ 



(No species of the genus with prosternum unarmed is known 

 from the region under consideration.) 



A. Caudal tibiae armed distad with three pairs of spurs. 



B. Subgenital plate very strongly and sharply produced latero-distad in 



sharp straight spikes which are weakly divergent, on the ventral surfaces of 



which productions are situated awl-like styles, distal margin of plate roundly 



emarginate mesad. (Subgenus Opeastylus) 



C. Form moderately slender. Fastigium of vertex little over one-half 



width of proximal antennal joint. Convex callosity of lateral lobes very 



broad. Swollen shelf above cereal tooth less extensive. Caudal femora 



with ventro-external margins armed normally with two and three spines. 



longipes (Redtenbacher) 

 CC. Fonii moderately robust. Fastigium of vertex somewhat more 

 than two-thirds width of proximal antennal joint. Convex callosity of 

 lateral lobes exceedingly broad. Swollen shelf above cereal tooth more 

 extensive. Caudal femora with ventral margins imarmed. 



vitticollis (Blanchard) 

 BB. Subgenital plate not produced disto-laterad, disto-lateral styles small 

 and filiform, distal margin of jjlate nearly or exactly transverse. 



(Subgenus Xiphidion) 

 C. Cerci armed with a heavy mesal (vertical) tooth so that its base is 

 entirely visible from above, this tooth situateil mesad. 

 D. Cerci with mesal jjortion not contrastingly swollen. 



' See p. 235 for a discussion of the species not represented in om- material. 



TRANS. AM. ENT. SOC, XLI. 



