426 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.57. 



Generic characters. — Clypeus truncate; nervulus postf ureal; areolet 

 present; propodeum with two raised, median longitudinal ridges; 

 propodeal spiracle three or more times as long as wide and about twice 

 its length from the base of propodeum; spiracles of the first tergite 

 close to the base, the distance between them greater than the distance 

 from one of them to the base of the segment ; first sternite fused with 

 the tergite at the base; second sternite with the median tubercles 

 of the female near the base; second tergite with lunulae; tergites 3 

 to 6 deeply angulately emarginate posteriori}^; abdomen of the male 

 parallel-sided and more than three times as long as the head and 

 thorax; ovipositor as long as or much longer than the body. 



The four recognized Nearctic species are easily distinguished by the 

 following key which is based mostly on color. 



TABLE TO THE SPECIES. 



1. Middle of the posterior margin of the heavily chitinized basal part of the first sternite 



extending in female distinctly beyond a line drawn tangent to the posterior 

 margin of the first tergal spiracle, in male extending beyond such a line by a 

 distance as great as that from the anterior margin of the first tergal spiracle to the 

 base of tergite; ovipositor not more than one and one-half times as long as body; 

 wings of male hyaline, of female hyaline with a cloud below stigma. 



greenei Viereck. 



Middle of the posterior margin of the heavily chitinized basal part of the first sternite 



in female distinctly before and in male beyond this point about the length of 



the line drawn tangent to the posterior margin of the first tergal spiracle; 



spiracle of ovipositor nearly twice, often thrice, as long as the body 2. 



2. Wings subhyaline with a large cloud below stigma; lateral marks on the tergites V- 



shaped; ovipositor about twice as long as body; anterior femora one-third longer 



than their tibiae lunator (Fabricius). 



Wings unicolorous 3. 



3. Stigma j^ellowish; wings subhyaline; mesonotum and mesepisternum in the male 



black; yellow of front of the head in the male restricted to orbital lines; female 

 with yellowish spots on the sides of the tergites; ovipositor about twice as long 



as the body nortoni (Cresson). 



Stigma black ; wings of male subhyaline, of female blackish ; mesonotum and mesepi- 

 sternum of male marked with pale; face of male mostly yellow; thorax and ab- 

 domen of female black; ovipositor distinctly more than twice as long as the body. 



atrata (Fabricius). 



MEGARHYSSA GREENEI Viereck. 



Megarhyssa greenei Viereck, Proc. U. S. Nat. Mus., vol. 40, 1911, p. 191, female, 

 not male. 



Type. — Cat. No. 13499, U.S.N.M. Discussion based on types and 

 specimens from localities listed below. 



The male which Viereck assigned to this species is in the wi-iter's 

 opinion a small male of lunator (Fabricius). Rearings and the struc- 

 tural characters of the first sternite show that the wings of the male of 

 greenei are without a cloud below the stigma. 



Distribution. — Harrisburg, Pennsylvania (type-locality, and mate- 

 rial collected by Fisher); Linglestown, Pennsylvania (Fisher), Cory, 



