NO. 1487. NORTH AMERICAN DIGGER WASPS— FERNALD. 383 



its posterior portion somewhat pubescent, fring-ed behind with sliort. 

 pale hairs; mesonotum somewhat punctured, with short, g-ra3nsh- 

 white hairs, and a faint median longitudinal groove on its anterior 

 third; scutellum rather more sparsely and finely punctured, with a 

 slight median depression, and covered with short, gTa3'ish-white 

 hairs; postscutellum pale yellowish- white, pubescent as far laterally" as 

 the groove at the side of the dorsum of the median segment, this 

 pubescence often being in part or entirely absent; dorsum of the 

 median segment finely, transversely aciculate, covered with yellowish- 

 white hairs longer than those of the mesonotum and scutellum; above 

 the petiole are two 3'ellowish-white pubescent areas partly confluent 

 on the middle line; petiole short, straight, black, with vellowish-white 

 hairs. 



Ahdomen. — Above, smooth, gray sericeous, very faintly punctured, 

 the last two plates bearing grayish and ))rownish hairs directed back- 

 ward; the terminal plate rounded, somewhat compressed on its pos- 

 terior half at the sides, forming a slight median ridge; beneath, glis- 

 tening, somewhat sericeous, with a few scattered grayish hairs, which 

 on the -fourth, fifth, and sixth ventral plates become tufts, one on 

 each side, on each plate; seventh plate somewhat emarginate on its 

 posterior margin; terminal plate rounded at the sides, acuminate at the 

 middle, behind, giving the plate the same form as that found in C. 

 liavltarsla. 



Wings. — Nearly hyaline, the front pair very slightly fuliginous; end 

 of the radial cell rather squarely rounded; cubital vein a mere shadow 

 beyond the ends of the cells; transverse median vein making more 

 than a right angle with the median vein in the hind wing; the cubital 

 vein only a faint shade bej^ond the transverse cubital; tegula? black, 

 the margin more or less ferruginous; pale sericeous near its center. 



Legs. — Coxa", trochanters, greater portion of the femora, last tarsal 

 segment and claws black or very dark; the rest of the leg and the tips 

 of the claws and the spines j^ellow ferruginous; coxa? sparsely punc- 

 tured, sericeous, with a few scattered hairs. 



Length.— Mi\\Q^, 18-22 mm, 



I have studied specimens of this species from Tennessee, Georgia, 

 and Mar^dand. Most of the specimens known were captured August 

 23, 1902, at Indian Head, Maryland, by Mr. J. C. Bridwell on the flow- 

 ers of Monarda i^iinctata Linnt^us in company with C. hridwdU H. 

 Fernald, and I am of the opinion that these two will ultimately prove to 

 be the two sexes of the same species. The yellow legs and general 

 api)earance of C. nudum are so suggestive of C.Jlav if arsis i\vAt it is 

 probable that specimens of the former species are in many collections 

 under the latter name. 



