130 PIMPLINE ICHNEUMONIDAE 



brown similar to that of the posterior orbits. In the hghter specimens the 

 rear margin of the mesoscutellum, an oblong spot in the centre of the meta- 

 Bcutellum and a line on its rear margin are rufous. In the darker specimens 

 these plates show no color markings. The propodeum is transversely striated 

 above, punctured below, with a median longitudinal depression extending ' 

 nearly to its posterior margin. The wings are fusco-hyaUne tinged with yellow, 

 and shghtly more fuscous nervures and stigma except at their base where 

 they are lighter. The areolet is small, petiolated, with the recurrent nervure 

 entering at its middle. The legs are pale rufous. The fifth segment of the 

 anterior and middle tarsi, and the claws are dark. The posterior femur 

 bears a dark spot at its extremity as does the tibia near its base. The tibia is 

 darker along its external surface completely enveloping its outer half. The 

 posterior tarsal segments are darker on their external surface, this dark color 

 increasing towards the claws, which are all dark. 



The abdomen is dark brown to black, transversely aciculated above, these 

 aciculations bending forward at the sides. The ovipositor is dark brown 

 with darker sheaths. 



The male of this species, from the collection of the U. S. National Museum 

 (here described for the first time), is shghtly less than half an inch long. The 

 head is black. The antennae are black at their base but become lighter and 

 somewhat larger toward their tips. From the base of the antennae down 

 to the clypeus the face is yellowish-white. This spot is prolonged to the ver- 

 tex in the form of bands margining the compound eyes. 



The thorax is black and poUshed. The sides of the mesothorax and meta- 

 thorax are densely punctured. The mesoscutellum and metascutellum are 

 transversely striated. The propodeum is transversely striated except along 

 the median, longitudinal depression, which extends nearly to its posterior 

 margin. Its sides are punctured. Nimierous short, erect, whitish hairs clothe 

 the thorax. 



The wings, legs and abdomen are as in the female. 



In size and general appearance M. canadensis resembles humida 

 more closely than the other Megarhyssae but the absence of white 

 spots on the side of the abdomen would serve to distinguish 

 it from humida as well as from atrata. Its dark brown to black 

 color with whitish color markings would distinguish it from 

 lunator, greenei, nortonii and mexicana. 



This species was originally described by Cresson as Rhyssa 

 canadensis, but the structure of its sternal plates, the fusion of 

 the pleura and sternum of the second abdominal segment, and the 

 acutely angled tip of the abdominal segments would seem to 

 place it in Megarhyssa. 



