356 HYMENOPTERA OF AMERICA. [PART I. 



black. A narrow margin on the anterior border of prothorax, 

 margin of tegulae, a transverse band on the middle of scutel, and 

 a narrow line margining the first two abd. segments, snlphur- 

 yellow ; that of the 2d complete beneath. Tibiae marked with 

 yellow. Wings smoky. 



9. Clypeus rounded, Tery coarsely punctured; its apex with 

 two quite approximate, very small teeth. 



Bess. a. diff. — This is an elongate species like 0. Tacubayee, 

 very distinct by its quite coarse punctures, even on the 2d abd. 

 segment ; much coarser even than in chichimecus. 



It differs : from Tacubayee by its sharply angulate prothorax, 

 crested scutel, bituberculate metathorax, and wider 1st segment, 

 as also by the margin of 2d segment which is truncate, not 

 arcuate; from 0. olmecus, by its thorax, not triangular, not so 

 wide anteriorly, not so attenuated posteriorly, its wider cup- 

 shaped 1st segment, and by the tubercles of metathorax which 

 are not sharp, but rounded and punctate : from tepanecus by 

 most of the preceding characters. So also from 0. chichimecus, 

 except by its 1st segment which is shaped as in this species ; the 

 post-scutel also is not vertically truncate ; its edge being an 

 anterior ridge, not a posterior one. This last character distin- 

 guishes it also from 0. acolhuus. 



Hab. The temperate part of Mexico. Oriental Cordillera 

 (Sumichrast). 



152. O. Olmecus Sauss. — Minutns, gracillimus, niger, punctatus ; 

 prothorace bidentato ; post-scutello medio transverse cristato ; meta- 

 thorace infere foveolato, superne tenuissime bituberculato, apiee bi- 

 spinoso ; abdominis lO segraento elongato, infundibuliformi ; capite 

 omnino nigro, pronoti margine antico, macula subalari, tegulorurn 

 limbo, scntelli abdominisque segmentorum 1', 2' (vel V, 2', 4') margiue 

 postico, flavis ; spinis metatboracis apicis tibiisque extus, flavis. 



%. Macula mandibulorum, clypeo, scapo subtus, flavis; flagello subtus 

 fulvo; clypeo latissime truncato. 



Odyn. Olmecus Sadss. Revue de Zool., XXII, 1870, 140, 33, %. 

 Total lengtb, 7 mm. ; wing, 5.7 mm- 



Small and slender, elongate. Having much the form of 0. 

 acolhuus. Head circular, rather swollen and concave behind. 

 Antennae inserted rather low. Thorax not veiy elongate, tri- 

 angular, wide exteriorly, attenuated posteriorly. Prothorax 



