EUMENID.f:. 165 



separate it at once from its allies, the longitudinal costje 

 of its transverse sulcature are very short, and the surface 

 of the segment, beyond the sulcature, is not raised above the 

 level of the latter, and is quite flat, or, if anything, con- 

 cave longitudinally ; in all the following species the segment 

 is more or less convex longitudinally. 



L. 8-14 mm. 



Very common, and generally distributed. 



0. pictUS, Curt, {oviventris, Tlioms.). — Very similarly 

 marked to the other species. of the genus, but with the 

 yellow colouring less abundant than in either of the pre- 

 ceding; as a rule, the thorax is entirely black, except the 

 anterior margin, which bears a narrow, yellow line ; the 

 abdominal bands are all linear throughout, and occur on 

 the first five segments, the sixth in the ? has an apical 

 spot, the second ventral segment has long, very strong 

 costse, across its transverse sulcature, and is rather strongly 

 convex behind it ; the tibiae and tarsi in the ? are reddish- 

 yellow, and are unspotted in both sexes ; the basal segment 

 is unusually wide in this species, and formed much as in 

 puriefum, from which the narrow abdominal bands, long 

 costffi and convex form of the second ventral segment at 

 once distinguish it. 



The broad basal segment, combined with the many- 

 banded abdomen, distinguishes it from any of the 

 following. 



L. 10-13 mm. 



Not common; Wandsworth. Bristol; Isle of ^Viglit ; 

 Portland; Weybridge ; (Smith). Colchester; {Harwood). 

 Rugby; [Morice). Plymouth and Bolthead; [Bignell). 

 Lancashire and Cheshire; (Gardner). Oxford; {li. C. L. 

 Perkins). Hastings; (Frish;/). Gloucestershire ; (Per/fins). 

 Norfolk ; {Bridymcni). Perth. 



0. trimarginatus, Zdt. — Like pictus, in the form of 

 the second abdominal segment, but rather more elongate, 

 and with the basal segment of the abdomen narrower in 



