214 NORTH AMERICAN SCELIPHRON (hYMENOPTERA) 



segments are finely pubescent along their posterior margins and 

 the third and sixth may be slightly pubescent also. These 

 segments are flattened or even concave, giving the abdomen a 

 compressed appearance ventrally. The genitalia are usually 

 withdrawn inside the posterior segments so as to be almost com- 

 pletely hidden. In conjunction with other characters they may 

 be used in separating males, but they have not been so employed in 

 this paper. The sixth or terminal segment of females is modified 

 to protect the genitalia, and at the same time to allow them free 

 play. The ventral portion of the terminal segment is longer than 

 the dorsal and its tip is somewhat squarely truncate. It has a 

 flap on each side which folds together dorsally, while the triangu- 

 lar dorsal portion fits over the basal part of the segment. 



Wings 



The wings are of medium size and may be either hyaline and 

 fuscous at the tips, or evenly colored in varying shades of brown 

 showing blue violet in certain lights. In this paper the nomen- 

 clature of veins and cells given by Cresson and used by Fernald 

 in his "North American Digger Wasps" has been followed. It 

 is not proposed to give a general description of the wings, but the 

 characters of systematic importance will be mentioned in the 

 table for separation and under the descriptions of the species. 

 A reference to the figures at the end of this paper will furnish all 

 the necessary details. 



Legs 



The legs are long and slender, especially the hind pair, and in 

 addition to the hairs and spines mentioned below, all the seg- 

 ments are clothed with fine to coarse sericeous hairs, dark or 

 whitish according to the species. 



All the coxae are clothed with somewhat long hairs, but have no 

 spines; the fore and middle coxae are both smaller than the 

 hinder pair, which articulate closer together than either of the 

 other two pairs. The trochanters are all smaller than their 

 corresponding coxae and have scattered hairs mostly on the 

 inside. The femora in the three pairs of legs are all stouter than 

 the tibiae with which they articulate, but while the fore and 

 middle femora are distinctly longer than the corresponding tibiae, 



