218 AMERICAN HYMENOPTERA. 



as the epimeron, and a large lower plate, called the epister- 

 num. A distinct sinuous suture separates these two plates. 

 This, the pleural suture, does not reach more than half-way 

 from the wing base to the base of the middle leg. The sur- 

 face of the mesopleuron is densely punctate and pilose. The 

 sternal region is somewhat infolded longitudinally in the 

 middle. In the middle of this infolding there is a fine longi- 

 tudinal elevated line. Between this sternal region and the 

 ventral ends of the pronotum is a small transverse membrane- 

 ous area. 



Metathorax. — This part of the thorax consists of a very 

 narrow series of plates compressed between the mesothorax 

 and the median segment or propodeum. The metanotum 

 is a single, narrow, transverse sclerite, widening on the 

 sides where it carries the wings. Its middle portion is over- 

 hung and partially concealed by the scutellum of the meso- 

 thorax. A slanting groove appears to separate the lateral 

 portions of this plate from the middle portion. These lateral 

 portions are densely punctate and rather heavily pilose, while 

 the middle portion is comparatively smooth and bears only 

 a small amount of short hair. 



The metapleuron consists of an upper and somewhat ante- 

 rior plate, supporting the hind wing, and a lower and poste- 

 rior plate, carrying the hind leg. The upper plate is elon- 

 gate-oval in shape and its surface is densely punctate ; it is 

 moderately densely pilose. The main part of the lower plate 

 is triangular, and from the corners of the triangle three long, 

 narrow extensions reach out. One of these extensions passes 

 between the middle and hind coxse and connects with the 

 metasternum ; another reaches up between the propodeum 

 on one side and the middle coxa and mesepisternum on the 

 other and connects with the upper plate ; the third extension 

 is shorter than the other two and reaches back between the 

 hind coxa and the propodeum. This lower plate does not 

 have much long hair. As Mr. Snodgrass has shown, no dis- 

 tinction as to epimeron and episternum can be made in the 

 consideration of these plates. 



The sternum appears to consist of a small, nearly trapezi- 



