JVorth American Hymenoptera. 377 



I 



Length over three tenths of an inch. 



^ Spot of the scutel interrupted or wanting ; antennae 

 beneath dull honey-yellow ; the two posterior bands of 

 the tergum generally confluent in their middles ; abdomen 

 longer and more slender than that of the female. 



Length three tenths of an inch. 



The sexes are more readily distinguished by the tip of 

 their abdomen than by the antenna3. I have nine males 

 and three females : two of the latter measure two fifths' 

 of an inch. The punctures of this species are larger and 

 more dense than in our other species. 



C. arcudtus. Metathorax with numerous parallel lines ; 

 tergum with yellow spots and bands. 



Inhab. Indiana. 



BoHy blacky with minute, dense punctures : front with 

 a wide glabrous interval between the silvery orbits : anten- 

 ncBy basal joint yellow^ with a black line near the inner 



base ; sixth joint arcuated, a little prominent inwardly at 

 tip : hypostoma yellowish-silvery : thorax with a slightly 

 interrupted line on the collar of a bright yellow ; a yellow 

 transverse line beneath the scutel : win^s a little tin^^ed 

 with dusky : metathorax with numerous, small, parallel 

 lines, arcuated at base, and transversely rectilinear behind, 

 extending upon the pleura beneath the wings : pleura 

 with two small yellow spots before : tergum with an 

 oblique somewhat arcuated, yellow spot each side of the 

 first segment ; an oblique elliptic one on the second seg- 

 ment each side ; a reclivate, transverse, lateral yellow 

 line on the third : remainin«: segments each with an en- 

 tire, slightly undulated, slender greenish-yellow band: 

 anal processes acute, very deeply and regularly ciliated : 

 feet yellow : coxcd and trochanters black : thighs at the 

 base black ; the black portion very small on the anterior 





VOL. I. PART IV. 



49 



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