'^00 PROCEEDINGS OF THE ACADEMY OF [1894. 



Head from above triangular, greatly produced behind the eyes 

 (the prothorax is longer than the dorsukuu, soutellum and 



postscutelluni combined) (j)r. Thigonopsis. 



Prothorax not as long, at any rate not longer than the dorsuluni, 



' Gr. ScEEiPHRON {=Pelopocus). 



Genus AMMOPHILA Kirby. 



Wings with two submarginal cells Gr. (,'oloptera. 



Wings with three submarginal cells. 



Second al)dominal segment elongate, forming with the first seg- 

 ment a long petiole Gr. Ammophii.a. 



Second abdominal segment more or less campanulate, the petiole 

 composed of but one joint (Jr. Psammophila. 



Tribe II.— AMPULICINI. 



The genus Ampulex is represented in North America by the sub- 

 genus Rhinopsls Westw.. It is distinguished by the rostrate clypeus 

 and by having two submarginal cells. The prothorax is long as in 

 Trigonopsis; the metathorax is many ridged and has very strong 

 transverse strife above and possesses two strong teeth. The first 

 submarginal cell is twice the length of the second. Marginal cell 

 with an appendiculation at apex. 



Subfamily PEMPHREDONIIsT^. 



The MimesidiB are here considered as representing a tribe of this 

 subfamily, and Miinesa Shuck, as a synonym of Pseu Latr. It is 

 impossible to separate these two genera as their characters vary, 

 particularly the neuration. It is true that the inner spur of hind 

 tibicC of Mimesa is peculiarly shaped, but this development will be 

 found in Psen, although in a lesser degree. 

 Anterior wings \\ith three submarginal cells; antennte situated far 



above the clypeus PSENINI. 



Anterior wings with two submarginal cells ; antenn;e close to base of 



clypeus PEMPHIIEUONINI. 



Tribe I.— PSENINI. 



Psen (= Miinesa), the only genus of this tribe, is easily distin- 

 guished by the characters given in the above table. The Psenini 

 further differ from the Pemphredonini bj' the peculiar inner spur of 

 hind tibiie. 



Tribe II.— PEMPHREDONINI. 



The tribe Pemphredonini comprises the greater number of the 



