206 HYMENOPTERA OF AMERICA. [PART I. 



3. Form slender, but the abdomen sometimes slender, sometimes 

 ovoid, especially among the %. The first segment cupuli- 

 form, narrower than the 2d, having the suture indistinct, 

 often presenting a transverse fluting bordered by two ti^aces 

 of sutures. 1 Concavity of the metathorax generally small, 

 its borders indistinct. 



(Group of the 0. occidentalis.) 



The insects of this category offer at times two sutural lines on 

 the first segment of the abdomen (the second usually interrupted) 

 so that one feels the need of classing them in my Division Sub- 

 ancistrocerus (Vespides, III, 206; I, 126). But as all their 

 affinities tend toward the group of the 0. fulvipes, I think best 

 to leave them in the same division. The sutures become wholly 

 double in certain species or indistinct, so that one does not know 

 whether or not to take them for simple rugosities and class the 

 insects which carry them in the subgenus Odynerus (Division 

 Stenodynerus). 



a. Suture of thef'st abdominal segment rather strong; excavation of the 

 metathorax somewhat distinctly margined. 



41. A. Guzmaili Saoss. — Parvulus, niger, dense cribratus ; pro- 

 noto bidentato; rnetanoto perrugoso, foveola orbiculari punctata, sub- 

 marginata instructo ; abdomine valde punctato ; primo segmento bisu- 

 turato ; secundi margine maxime cribrato, subcanaliculato; prothoracis 

 seguientorumque 1', 2' limbo, post-scutello, puncto frontali et frequenter 

 subalari, flavis ; pedib :s fulvo-variis ; tegulis maxiinis, navo-margiuatis. 



Odynerus Guzman i Saoss. Rev. de Zool.. IX, 1857, 275, % . 



Total length, 7 mm. ; wing, 6 mm. 



%. Small. Prothorax wide; its anterior border concave, 

 turned up, forming on each side a little tooth directed obliquely 

 forward. Head and thorax before coarsely cribrose throughout. 

 Scutel divided by a groove. Metathorax feebly prolonged behind 

 the post-scutel, then vertically truncate, extremely rugose ; its 

 middle occupied by a circular concavity, shining and cribrose 

 with punctures ; a little rimmed, especially at the summit. First 



1 Sometimes the two sutures are feeble and difficult to distinguish. It 

 is necessary in that case to turu the insect into the proper light to per- 

 ceive them. 



