NO. 2173. A REVISION OF THE B EM B WINE WASPS— PARKER. 119 



radius in most cases an acute angle, but in some cases a right angle» 

 The second submedian cell is about equal in length to the first and 

 increases in width from its proximal to its distal extremity. 



On the posterior wing the retinaculum, composed of a row of small 

 booklets, arises at the origin of the radial vein. The median cell is 

 greatly elongated, and from its distal end two short veins extend 

 toward the distal border of the wing. The cubitus arises distal to the 

 end of the submedian cell, whose posterior distal angle, formed by 

 the submedian and submedian cross veins, is obtuse. 



The ground color of the body is black, but in teneral specimens this 

 may appear brown. The color of the maculations varies from pale- 

 yellowish white to rich orange yellow. 



KEY TO SPECIES. 

 Males. 



1. Process on second sternite long and curved (fig. 218); clypeus, large spot on 

 mesopleura and large discal spots on scutum yellow aurata. 



1. Process on second sternite otherwise formed; above combination of maculations 



not present 2. 



2. Process on second sternite hirsute; genital stipes as in fig. 224 hirsuta. 



2. Process on second sternite smooth; genital stipes as in fig. 226 monodonta. 



Females. 



1. Pubescence on head, thorax, and median segment unusually long and dense, very 

 consnicuous on dorsum of median segment hirsuta. 



1. Pubescence not unusually long and dense 2. 



2. Clypeus, scape, mesopleura, and large discal spots on scutum yellow aurata. 



2. Combination of maculations as given above not present monodonta. 



MICROBEMBEX MONODONTA Say. 



Figs. 6, 219, 225-230. 



Bembex monodonta Say, Nar. Exp. St. Peters River, Append., 1824, p. 335. 

 Bemhex ciliata Lepeletier, Hist. Nat., vol. 3, 1845, p. 279. 

 Bembex monodonta LeConte, Say's Complete Writings, 1859, p. 226, male. 

 Bembex argentifrons Cresson, Proc. Ent. Soc. Phila., vol. 4, 1865, p. 141. 

 Microbembex monodonta Patton, Bull. U. S. Geol. Surv., vol. 5, 1879, p. 362, 

 Monedula nigrifrons Provancher, Add. Faun. Can., p. 362, male, female. 

 Bembex monodonta IIandlirsch, Sitz. Akad. Wissensch. Wien, Math.-Nat. CI., 



vol. 102, 1893, p. 882. 

 Microbembex monodonta Fox, Proc. Acad. Nat. Sci. Phila., 1895, p. 363. 

 Microbembex monodonta (and varieties) Johnson and Rohwer, Ent. News, 



vol. 19, 1908, p. 374. 



Male. — Black: Labrum in part or entirely, apical border of clypeus 

 or entire clypeus, tubercles, narrow fine on posterior border of prono- 

 tum, spot on tegulae, lateral line above base of wings on scutum 

 variable in extent, sometimes pair of discal marks on scutum, lateral 

 rectangular spots on scutellum variable in size, fascia on metanotum, 

 curved fascia or pair of obhque lines on dorsum of median segment, 

 sometimes postero-lateral angles of median segment, very fre- 



