Fossorial Hymenoptcra of North America. 371 



middle of the subcostal area; 2d median cell much shorter than in 

 Orabro; 2d submedian space shorter, and its outer side much more 

 oblique and curved than in Orabro, when it is more or less angular. 

 Legs slender, smooth, joints not slightly spinulated. 



Abdomen longer than the head and thorax together, slender and 

 narrow, subclavate, slightly pedunculate, basal joint being narrower 

 and longer than in Crabro, and the entire region more arcuate ; tip 

 spatulate. 



9 . Head transversely oblong, being a little more than one-half as 

 long as broad, broader than in % ; front even with the margin of the 

 eyes; quadrilateral, but rounding inwards a little, towards the inser- 

 tion of the mandibles; front between the eyes rather narrow triangu- 

 lar median line deeply impressed, does not spread out so broadly on 

 the vertex as usual ; clypeal region one-half as broad as the head ; 

 clypeus itself trapezoidal, full as long as broad, well raised in the 

 centre; eyes rather narrow, not globose as in Crabro; antennae nor- 

 mal, thickening a little towards the tip ; joints cylindrical, a little en- 

 larged in the middle ; mandibles as usual, bidentate, teeth equal; palpi 

 not very slender, joints broad, compressed. Femora more swollen and 

 spinulated than in % . There is a tendency in the $ abdomen to 

 thicken towards the tip, where in Crabro it is thickest in the middle ; 

 tip triangular, acutely produced, flattened above with prominent lateral 

 ridtres. 



o 



This genus may be easily distinguished from Crabro, by its shorter 

 head, which is much more transverse, being less cubical; the eyes 

 are less globose, more aligned with the surface of the front, or epiera- 

 nium. and smaller and narrower; the front is not so deeply impressed 

 by the antennal groove, and the 2d joint of the scape of the antennae 

 is more cylindrical, less liable to become angular, as are the terminal 

 joints which are cylindrical, where in Crabro they are sometimes den- 

 tate beneath. One of the best distinctive characters lies in the very 

 narrow clypeal region, as in this genus the eyes completely cover over 

 the lateral clypeal region which is so characteristically exposed in 

 Crabro, while the clypeus itself is longer, with its front edge more 

 rounded and deeply toothed. The palpi are smaller and weaker than 

 in Crabro, besides being more compressed. The thorax is more pro- 

 duced behind, as is the abdomen v also, being longer than the anterior 

 part of the body, while in Crabro, though this is not a constant char- 

 acter, the abdomen is apt to be either equal in length to both the head 

 and thorax taken together, or even shorter; the triangular tip of the 



