60 HYMENOPTERA OF AMERICA. [PART I. 



Head much compressed i ransversely, thaf is, wide, but not thick, 

 nor enlarged; the eyes very convex and entirely covering- the 

 cheeks. Clypeus always longer than wide, with a variable 

 termination (bidentate, indented, truncate, or rounded). 



Thorax variable, globular, or long quadrate, rarely compressed, 

 l)u! always without spiniform angles. 



Abdomen lengthened pediculate. The first segment forming a 

 linear or subcampauulate petiole, about as long as the thorax; 

 the remainder of the abdomen pyriform. 



This genus is very abundant in species, and is found over all 

 ,1 "' our globe. It is broken up into peculiar types; of 



which one (Division Alpha) is represented everywhere, and the 

 others solely on one part of our planet. These types are con- 

 nected by natural transitions which embarrass one in assigning 

 them very fixed limits. 



I be Eumenes are well represented on the new continent. Of 

 six divisions 1 into which I have divided the genus, four are found 

 "ii the Western Continent, but the divisions Pachymenes, 

 Omicron, and Zeta, are only represented in the tropical parts of 

 A-raerica. The insects, peculiar to the Division Omicron, inhabit 

 ■ill the equinoctial parts of the continent ; and those which belong- 

 in the Division Alpha, extend themselves over the two American 

 continents within their most extended limits. 



Division PACHYMENES. 

 (Sapss. Vespides I, 73, III, 158.) 



Al " 1 " 1 """ raucn depressed, never compressed, petiole widened 

 or campanula!-, parted by a groove ; its binder margin having 

 usually a transverse groove; clypeus generally bidentate ; body 

 smooth, silky, and chatoyant or velvety ; wings large. (American 

 type.) 



Th ise insects have tn " appearance of Polybia, as the Monte- 



■"•"'" have tha1 of SijnoBca. It is es daily by this appearance 



thai one recognizes them and the semblance holds good in the 

 ''"l"'"^'" 1 form of the Petiole and in the pyriform abdomen as 

 well as the silky appearance of the body. 



1 ' '1" not couiH the Division Pareumenes, which is worthy to form a 

 genus (Etudes Bur la Famille des 7espides, III, 133). 



