REVISION OF THE GENUS EXETASTES CUSHMAN 249 



KEY TO NORTH AMERICAN SPECIES OF EXETASTES 



The following key to the North American species of Exetastes 

 embodies an attempt to classify the species in natural groups. This 

 has necessitated rather long couplets, but it is hoped that the result 

 will prove more satisfactory than a purely artificial key. In these 

 group definitions color has been employed only as a supplementary 

 character. Within the groups color is more freely used since it 

 frequently furnishes the most easily observable characters. Because 

 of the uncertainty as to its proper position, Exetastes caudatus (Pro- 

 vancher) is omitted from the key. 



1. A high thin carina between antennae; second discoidal cell very 



short, the second recurrent being nearly or quite as long as 

 basal abscissa of subdiscoideus; areolet unusually small; apical 

 carina of propodeum very strong 2 



No carina between antennae; second discoidal cell with recurrent 

 much shorter than basal abscissa of subdiscoideus; areolet of 

 normal size; apical carina rarely very strong 4 



2. Clypeus not obviously divided into basal and apical portions, the 



apical portion represented by a narrow, sharply inflexed 

 margin; occipital carina reaching hypostomal carina; thorax 

 very coarsely, densely, and evenly punctate; recurrent dis- 

 tinctly basad of middle of areolet; ovipositor sheath hardly 



half as long as first tergite 1. carinatifrons, new species 



Clypeus distinctly divided; occipital carina not reaching hypo- 

 stomal carina; thorax less coarsely and densely punctate; recur- 

 rent at or very near middle of areolet; sheath nearly or quite 

 as long as first tergite 3 



3. Temples in female receding at about 45° and nearly flat, less 



strongly sloping and more strongly convex in male; postocellar 

 line hardly longer than ocellocular line and distinctly less than 

 twice the diameter of lateral ocellus; antenna with 40 joints or 

 less, subapical joints in female hardly longer than thick; wings 

 yellowish infumate with apical fascia little darker. 



2. septum, new species 

 Temples in female more strongly receding; postocellar line dis- 

 tinctly longer than ocellocular line and fully twice diameter of 

 an ocellus; antenna with 46 joints, subapical joints distinctly 

 elongate; wings nearly hyaline with apical fascia very distinct. 



3. carinatus, new species 



4. Head and thorax mat, extremely finely and densely punctate, 



with very dense, fine pubescence; eyes distinctly divergent 

 below; abdomen very broad, first tergite triangular, about as 

 broad as long, others transverse; black species with a distinctly 

 grayish appearance due to the dense pubescence; all tergites 



broadly margined with yellow 4. lasius, new species 



More coarsely punctate and usually shining, with pubescence 

 sparser and coarser; eyes at most very slightly divergent 

 below; first tergite distinctly longer than broad; not so 

 colored ^ 



5. Clypeus narrow, divided into basal and apical portions only by 



sUght difference in sculpture; apical carina of propodeum 



