92 HYMEXOPTERA OF AMERICA. [PART I. 



Hab. Mexico. Oriental Cordillera. Moyoapam. 



This is a sort of mimic species. It bears the coloration and 

 rather the form of some Polybia, f. i., P. fasciata Lep. We 

 know a Cerceris of the same country' which shows the same 

 peculiarity. Entomologists ought to study whether these insects 

 of mimic resemblance do not have some relationship in their 

 habits. 



Division ALPHA (Eumcnes proprie dicti). 

 (Sacss. Vespides, I, 28; III, 128, 137.) 



Mandibles long, dentate. Clypeus pyriform, notched or trun- 

 cated at the extremity. Antennae generally inserted above the 

 middle of the head. Ocelli arranged in a broad triangle. Thorax 

 generally longer than wide; squarely truncated before, but with- 

 out salient angles ; metathorax convex, but not prolonged, rounded 

 and having two distinct convexities separated by a channel. 

 Petiole of the length of the thorax, linear at its base ; about the 

 middle rather suddenly" swelled into the form of a club or of a 

 truncate pear, or campanulate; feebly bidentate (or bituberculate) 

 in the middle, generally bordered by a salient cordon; the swell- 

 ing generally parted by a groove, and having an impressed point 

 before the margin. Pyriform part of the abdomen globular or 

 compressed, or at least not much depressed. Antennae of the 

 males terminated by a hook. 



The body of these insects is in general densely punctured and 

 covered with thick sub-woolly hair, and the clypeus of the males 

 is usually yellow, clothed with a silvery pile, while among the 

 females it is only marked with yellow. But these characters suffer 

 certain exceptions among the American species. 



As it was said, there is no regular limit between this group and 

 the Division Omicron, but if we compare the extreme forms of 

 both, as for instance E. globicollis or aviculus with E. globulosus, 

 there will be an easy distinction of both types, which exists no 

 longer if we compare all the species. In general terms we can 

 say that here the thorax is often more lengthened ; the metathorax 

 more parted; the petiole more campanulate ; the extremity of this 



1 Cerceris simulans Sacss. Reise d. Oesterr. Fregatte Novara. Hvmenopt., 

 p. 81, No. 1, fig. 53. In tins, even the forms of Cerceris are so modified as 

 to approximate to those of Polybia, the abdomen becoming elongate-peti- 

 olate. 



