98 HYMENOPTERA. 



basal projection, or basal pedicel (BP), altho free, is also very 

 similar in all species. The apical projection, or distal pedi- 

 cel, however, shows a wide range of modifications. When 

 well developed it is rather long and slender, terminating in 

 two apical lobes (A), which furnish excellent characters. 

 More detailed descriptions of the various types of ventral 

 plates will appear under their individual headings. 



Thoracic nomenclature. — The nomenclature adopted in the 

 present paper is that proposed by Snodgrass in, " The Thorax 

 of Hymenoptera," (Proceedings of the U. S. National Mu- 

 seum, XXXIX: 37-91, 1910). The most important changes 

 from the old nomenclature are in the thoracic segments, as 

 shown in figure 10. The area formerly designated " post- 

 scutellum " is now called the " metanotum ", and that desig- 

 nated " metathorax " has been changed to " propodeum ". 

 It is important to note these changes in comparing the ac- 

 companying descriptions with former ones, especially the 

 change in the term "metathorax" to indicate an entirely 

 different segment. Other changes will be evident from the 

 figure. 



To facilitate discussion of the face markings, and the parts 

 of the face I have applied the term "lateral area" of the 

 face, to that portion between the orbit, the clypeus and supra- 

 clypeal space, and below the base of the antennal socket, on 

 each side. This does not include any space above the an- 

 tennal socket, whether covered by the face marks or not. 



KEY TO MALES.— Based on external characters. 

 Very large, scape enormously swollen, "heart shaped", covering 



face above antennal sockets (fig. 92) basalis. 



Lateral face marks conspicuously divergent from orbital margin above 



and curving around antennal sockets 1. 



Lateral face marks confluent with or not noticeably divergent from 



orbital margin 4. 



1. Lateral face marks clavate above or stout, not tapering to tip 2. 



Lateral face marks short above, upper extensions not clavate, but 



tapering to a point at apex 3. 



2. Large, upper extensions of lateral face marks greatly enlarged at 



apex, (fig. 91), antennal sockets very close together, scape 

 and collar with yellow, scape dilated conspiciia, n. sp. 



