236 HYMENOPTERA OF AMERICA. [PART I. 



the thorax. One should perhaps consider this species as a variety 

 of the 0. nasidens? yet it appears to us to constitute a local 

 species. 



Bab. The isle of Cuba. 6 9,3$. 



" The nest of this species is somewhat of an oblate spheroidal 

 shape, constructed of flue earth, of a beautiful fawn-color. It is 

 attached to a slender twig and measures 4^ by 6 lines; sometimes 

 two nests are attached close together, to the same twig-; the 

 outer surface is uneven, and on the upper side there is a stout 

 peduncle, by which the nest has been attached to another body. 

 The opening made by the imago in its escape is large and always 

 on the side of the nest." (Cresson, 1. c.) 



b. Metaihorax rounded, not forming on each side a dentiform angle. 



6®. O. ArgentifilllS Sacss. — Niger, confertiin punctatus ; inetauoto 

 postice rugoso, rotundato, utrinque angulo nullo; superne utrinque 

 acute-marginato, can this a post-scutello fissura sejunctis ; pronoti 

 abdominisque segmentorum 2'-5 i margin e postico flavo-limbato ; alis 

 hyalino-ferrugineis, apice grisescentibus ; tegulis ferrugineis. — £. Cly- 

 peo trnncato, fiavo ; puncto frontali ; scapo subtus, tibiis antiee, flavis. 



Odyn. Argentinus Sadss. Rev. et Mag. de Zool. XXII,1870, 5G, 6 J . 



9 . Total length, 11 mm. ; wing, 9.5 mm. 

 % . Total length, 10 mm. ; wing, 8 mm. 



9. Head and thorax densely and rugosely punctured, sha- 

 greened; the punctures small. Thorax a little longer than wide. 

 Post-scutel truncate, very short and transverse, crested and a 

 little crenulate. Metathorax posteriorly excavated, rugose, but 

 with arcuate edges, circular, forming no lateral angle whatever; 

 the lateral ridges sharp in their upper half, each terminating in a 

 tooth separated from the post-scutel by a deep fissure. Abdomen 

 of equal width from base* up to the end of the second segment, its 

 base truncate and rounded; the whole very finely punctured, with 

 very short hair and with sericeous gray pile ; the hinder margin 

 of 2d segment sometimes slightly depressed or very slightly cana- 

 liculated, and a little more strongly punctured than the base. 



Insect deep black, with very short gray hair. Antenna? black; 

 a line on the hinder margin of prothorax and a regular band on 

 the hinder margin of segments 2-5 yellow ; beneath only a mark 

 on each side of the margin of the 2d segment ; tegulae margined 

 with yellow or ferruginous. Anus black. Legs black ; articu- 



