288 HYMEXOPTERA OF AMERICA. [PART I. 



summit of the mandibles, two on the summit of the clypeus, a 

 dot on the front, another behind each eye, a narrow border on 

 the prothorax, wing scales, a dot under the wing, post-scutel, a 

 quite regular narrow bordering of the segments of the abdomen, 

 and 2d and 3d tibiae without, whitish. Tarsi and knees ferrugi- 

 nous. Antennae wholly black. Wings transparent, or subsmoky ; 

 a brown spot on the wing scale. 



Tar. a. Clypeus ornamented with a whitish arcuate band on 

 the summit. The bordering of the first segment mingled with a 

 white lateral dot, 



b. The last segments without border. 



c. Xo spots under the wing. 



%. Clypeus bidentate, yellow; labrum, mandibles, the frontal 

 spot, a line on the scape of the antennas, the hook of antennae, 

 tibiae, tarsi, intermediate thighs beneath, and coxae 2, 3, yellow. 

 No spots under the wing. 



Bess. a. cliff. — This species resembles above all — 1st the 0. 

 foraminatus, from which it is distinguished by its less concave 

 metathorax, the concavity less rugose, having the superior ridges 

 straight and pronounced, its antennae black, its ornaments white, 

 etc. — 2d, from the Ancistrocerus albophaleratus, which is almost 

 identical in form and livery, but from which it is clearly distin- 

 guished by the absence of the suture on the first abdominal seg- 

 ment, and which has the scutel spotted with whitish, with the 

 post-scutel black. — 3d, from the 0. Megsera, which has the 

 posterior plate of the metathorax much more concave, and of a 

 rounded not angulate form, the wings black, and only two whitish 

 bands on the abdomen. 



Hab. The northern United States. Connecticut (E. Xorton), 

 Illinois (Kennicott), 3 9,1$. (1 9 from Fort Te.jon. Latit. 

 35°, longit. 119°; altit. 4G00 feet.) 



Observation. — This species, so very near by the form and livery 

 to the Ancistrocerus albophaleratus, approaches xevv much also 

 in the form of the metathorax to the Ancistrocerus group of the 

 species cited. One would say that these two species issue from 

 the same stock, of which the form of the 1st abdominal segment 

 is bifurcate, while the livery has continued the same. 



