J. H. MERRILL 143 



smooth or striated. The antennae are dark brown to black. Some are all 

 black, some have a suggestion of white, some one or two segments that are 

 white, while in others there may be a number of distinct, white segments 

 forming a band on the antennae. The individuals having this last-named 

 characteristic have been regarded by some as forming a separate species, 

 Rhyssa albomamdata. 



The thorax is dark brown to black. There is a variable amount of thoracic 

 punctures and striations. The prothorax is bordered above and below with 

 a varying amount of white. In some the sides of the prothorax have such an 

 amount of white that the dark ground color only shows as a spot in the center. 

 The mesonotum is immaculate. On the center of the mesoscutellum is a 

 square white spot, and usually there is a white Une on the rear margin of the 

 entire plate. There is an oblong white spot on the center of the metascutellum 

 (postscutellmn) and this plate may or may not have its rear margin marked 

 by a white line. The tegulae and a raised spot beneath the fore wings are 

 always white. On the mesopleuron just below the attachment of hind wing 

 is a white spot and another just above and in front of the middle coxae. The 

 size of these spots is variable and they may even coalesce, margming the post- 

 erior border of the mesopleuron. There is a variable white spot on the side 

 of the metathorax and another just above it on the propodeum. In some 

 specimens there is a median longitudinal depression on the notum of the pro- 

 podeum; in others it is suggested, while in some it is absent. The wings are 

 hyaUne sometimes tinged with yellow. The nervures and stigma are fuscous 

 except at their base, where they are paler. The shape, size, and even the pres- 

 ence of the areolet are variable. The recurrent nervure is usually interstitial 

 with the outer transverse cubital nervure. In some the latter nervure is 

 present and assists in forming the areolet, in others but a stub of it remains 

 while in some cases it is absent. In some cases the areolet is petiolated, 

 receiving the recurrent nervure in its middle. The legs vary from light yellow 

 to rufous, the coxae from white to black with white spots. In general the 

 posterior legs are darker than the others. The color is even more variable 

 in the legs than in the thorax. The abdomen is dark brown to black, lustrous, 

 and finely, transversely aciculated above. The lower borders of the pleura 

 of the second segment are each margined with a white band, which bends 

 upward at its posterior margin and usually meets its fellow of the opposite 

 side, above. The third segment is sunilarly marked except that the bands do 

 not quite meet above. Usually on the fourth, fifth, sixth, and seventh seg- 

 ments these bands are interrupted so that a spot is formed on the upper 

 side of the pleuron, while its lower border remains marked with a white band. 

 In some, the spot and band are connected on the seventh segment. On the 

 last segment the white marking is continuous along the posterior margin but 

 does not meet its fellow above. This line is not always continuous. The 

 ovipositor is shghtly longer than the body, dark brown to black, with darker 

 colored sheaths. 



The male differs from the female in that the face below the antennae is 

 whiter and the anterior coxae and femora are lighter colored. 



TRANS. AM. ENT. SOC, XLI. 



