270 HYMENOPTERA OF AMERICA. [PART I. 



Clypeus, a line on the mandibles, and the line on the scape of 

 the antenna3, of a pale tawny. 



Var. No spots on the front nor on the metathorax. 



Bess. a. cliff. — This Odynerus is easily recognized by its livery 

 and its velvety aspect. 



It differs from the 0. Guerreri by its conical abdomen and by 

 the superior salients of the metathorax ; from the 0. foramina tus, 

 by its metathoracic concavity, not nearly so well limited, and by 

 the salients of the superior angles, which are not sharp, but rugose, 

 obtuse, and separated from the post-scutel, not by a little fissure, 

 but by a wide notch. By its livery it recalls the 0. otomitus, 

 which is near to it, but differs in its conical, sessile abdomen, 

 having the first segment wide and truncate, in its great size, etc. 



Eab. The hot and temperate parts of Mexico. (I caught 4 %, 

 2 9 in the valley of Mexlitlan.) 



C. Hinder plate of metathorax no longer margined superiorly 

 by sharp edges; the superior edges blunted and effaced by 

 the rugosities of the latero-superior faces, which continue 

 over the edges down on to the posterior face, and lose them- 

 selves in its concavity, instead of being separated from the 

 hinder face by the sharp edges. (Lateral angles still 

 existing. ) 



92. O. arvensis Sauss. (Fig. 1G, 16a.) — Medius, niger, grosse punc- 

 tatus ; 0. dorsali simillimus at minor; ore, macula froutali et post- 

 oculari scapoqne subtns, rufis vel flavis ; pronoti margine, post-scutello, 

 maculis.2 metanoti abdominisque segmentis 10-3° vel 10-4° flavo- 

 limbatis, 20-4° crassissime punctatis ; primi margine utiinque aucto et 

 rufo-vario. pedibus flavis, liasi nigris, alis fuuiosis. 



9- Clypeo valde latiore quam longiore, truncato, grosse punctato, nigro 

 vel rufo ; snperne fascia flava. 



% . Clypeo polygonali paulo latiore quam longiore, flavo, truncato, apice 

 dentulis 2 distantibus instructo. 



Oclyn. arvensis Sauss. Rev. de Zool. XXT, 1869. 



9. Total lengtb, 14, 12 mm. ; wing, 11, 5-9 ram. 

 % . Total lengtb, 12, 5-9 mm. ; wing, 9-7 mm. 



9. Form rather near to that of 0. Boscii, but smaller. The 

 abdomen a little more conical ; the 2d segment shorter and 

 more coarsely punctured; its inferior border a little lamellate 



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