134 IIYMENOPTERA OF AMERICA. [PART I. 



Var. Scutel aud metathorax with two whitish spots. 



Bess. a. diff. — The Monobia ±-dens is very difficult to distin- 

 guish from the Odynerus bidens ; however, one can always 

 recognize it — 1st, by its clypeus armed with two teeth %, with 

 two salient angles ? ; 2d, by its abdomen, punctured more 

 strongly and throughout, especially on the anterior face of the 

 first segment and upon the second which does not offer an arcuate 

 band of strong punctures along its border; 3d, by its maxillary 

 palpi which have but five articles and the labial having the 4th 

 article rudimentary and soldered upon the third. Compare also 

 Odynerus quadrisectus. 



Bab. The United States. A species common in all the 

 eastern part of the country. 



I possess a great number of specimens taken in all the Eastern 

 States, in New England (Xorton), in Illinois (Walch, Kenni- 

 cott), in Tennessee (Freudenreich-Falconnet, Fuchs), in South 

 Carolina, Louisiana (author), Florida (Xorton). 



B. Abdomen ovalo-eonical ; the first segment more rounded, less 

 truncate, less sessile. Metathorax rounded; its concavity 

 not bordered above by trenchant ridges. 



a. On each side of melatlwrax a dentiform angle. 



6. M. anglllosa Sauss. — Valida, nigra, punctata; clypeo £ piriformi, 

 punctato, infere striato, subbicarinato, apice biangulato, % apice 

 truncate- ; metanoto velutino, bidentato, excavatione punctata instructo, 

 nullomodo acute marginata; abdomine ovato-conico, sericeo, metanoti 

 angulis utrinqne fascia laterali aurantiaca; genibus, tibiis et tarsis 

 praecipue anticis, testaceo-variis ; alis fusco-cyaueis. 



% . Antennis subtus ferrugiueis, scapi fascia fiava ; tarsis subtus sulfureis. 



Monobia an gulosa Sauss. Vespides, I, 98, 6; pi. xv, fig. 5 (1852) ; III, 1G9. 

 Total length, 23 mm. ; wing, 18 mm. 



Large. Clypeus strongly punctured, almost in stria? ; piri- 

 form, at the extremity truncate, almost biangulate. Between the 

 antennae is a kind of tubercle, grooved above. Metathorax form- 

 ing on each side a compressed tooth ; the concavity a little striate 

 and punctured, but the superior edges effaced ; roughly punctured. 

 Head and thorax densely punctured; the metathorax very rugose 

 above. Abdomen conical as among the true Rhynchium, shining, 

 punctures scattered ; the border of the 2d segment and the fol- 

 lowing on the contrary very densely punctured, dull. 



