290 HYMENOPTERA OF AMERICA. [PART I. 



meta thorax, more slender form, etc. 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). 



IJ. 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-scutellar teeth, although still separated 

 from the post-scutel by a groove. 



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

 and rouyh edges. Abdomen conical, its ba^e sharply truncate. 



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

 nitido grosse punctate- ; metanoto perrugoso, baud bideutato, foveolse 

 striatae marginibus prominulis sed perrugosis, Laud acutis ; abdoiuine 

 conico, segmentorum 2-5 margine percrasse cribratis; macula frontal i 

 et post-oculari, prouoti et abdominis segmentorum I s — 4' limbo, macula 

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

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

 "valde puWfato, autice attenuate, truncato; mandibulis, oculorum 

 margine intus, scapo subtus, llavis. — J ?. 



OJyn. 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, bnt the thorax 

 shining and more coarsely eribro>e 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 sharp 

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

 coarsely cribrose, as are also the following segments. 



