200 IIYMENOPTERA OF AMERICA. [PART I. 



metathorax, more slender form, cte. This is rather an interme- 

 diate type between Division Odynerus and Stenodynerus, by the 

 quite linear form of its post-scutel, not flattened above and ridged 

 posteriorly; and by its abdomen, although sessile and truncate 

 at base, having the 1st segment more punctured than the 2d at 

 base. 



Hab. California (E. Norton). 



B. Posterior plate of metathorax no longer margined with sharp 

 ridges, but having its edges blunted by the rugosities or the 

 punctures (or not rugose); and the summit of the ridges no 

 longer forming post-scut ellar teeth, although still separated 

 from the post-scutel by a groove. 



a. Posterior plate of metathorax much, excavated, margined with salient, blunt, 

 and rough edges. Abdomen conical, its base sharply truncate. 



105. O. ESfiOlestMS Sauss. — Niger, tomento cinereo hirsutus ; thorace 

 nitido grosse punctato; metanoto perrugoso, baud bidentato, foveolse 

 Striata marginibus prominulis sed perrugosis, Laud acutis ; abdomine 

 conioo, seginentoruru 2-5 margine percrasse cribratis; macula frontali 

 et post-oculari, pronoti et abdominis segmentoruin l'-4' limbo, macula 

 subalari, tegulis, scutelli maculis 2, post-scutello, metauoti suniiui 

 punctis 2 pedibusque, flavis. — £ . Clypeo latiore quam longiore, flavo, 

 valde punctato, antice attenuato, truncato ; mandibulis, oculorum 

 margine intus, scapo subtus, flavis. — £ ?. 



Odgn. molestus Sauss. Revue et Mag. de Zool. XXII, 1870, 61, 19, % . 



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



%. Size and appearance of the 0. arvensis, but the thorax 

 shining and more coarsely cribrose with more separated punctures. 

 Post-scutel crenulate. Metathorax but little retracted, very 

 rugose; its posterior face not bidentate, strongly excavated, the 

 borders very salient, but not at all trenchant; being on the 

 contrary blunted, rounded by very coarse punctures. At times the 

 borders are a little channelled because of these punctures; their 

 ♦summit is separated from the post-scutel by a fissure, but does not 

 form any salient angles. Abdomen conical, having the same form 

 as the 0. arvensis; the first segment truncate, having a sh 

 angle; the 2d very short, its posterior border impressed and very 

 coarsely cribrose, as are also the following segments. 



