Fossorial Ilymcnoptcra of North America. 413 



without. The 1st sub-costal are large and oblonsr. 1st sub-median is 

 regularly rhomboidal. 2d sub-median rather narrow, the outer side 

 oblique and curved outward. In the secondaries the recurrent is situ- 

 ated farther in towards the middle of the rin»; than usual. 



Abdomen very long, clavate, nearly a third longer than the rest of 

 the body, thickest towards the end ; 1st ring pyriform, swelled more 

 than the other rings. 



Synopsis of the Species. 



A. Abdomen entirely black. 



Wings purplish : no enclosure on the propodeum T. politum. Say. 



Wings clear: propodeum with a distinctly, minutely 



lineated enclosure T. clavatum, Say. 



Body black throughout ; propodeum smooth, with mi- 

 nute and sparse punctures T. excavatum, Smith. 



Smaller than usual, propodeum rugose, striated, legs 



black T. frigidum, Smith. 



B. Abdomen ringed with red. 



Prothorax. propodeum and legs red: 2 basal rings red... T. collinum, Smith. 

 A narrow hand of red on 2d abdominal ring; clyjieus 



excavated T. rubrocinctus, Pack. 



14 abdominal rings red: elypeus tridentate T. tridentatum, Pack. 



Trypoxylon politum. Say. 



T. politus, Say, Bost. Jour. Xat. Hist. I, Xo. 4. p. 373. (1837). 

 not T. albitarse, Fabr. 



T. albitarse, Beauv., Ins. Afrique et en Amerique, PI. iii, Hym. fig. 1. p. 115. 

 (1805). 



Head of the usual proportions, front black, very finely punctured; 

 with a coarse, sparse pubescence ; elypeus raised, ridged mesially ; 

 edge thickened; polished black, with few hairs; thorax black, smooth 

 and highly polished, very free from silvery pubescence, especially the 

 prothorax; propodeum smooth and polishad ; enclosure obsolete, 

 scarcely marked, with a rather thick and short pubescence evenly dis- 

 tributed over the entire surface. Tegulre black; wings smooth, dark, 

 with a deep violaceous tinge. Legs black throughout, hind tarsi of a 

 pale testaceous. Abdomen as usual, though more stoutly clavate, with 

 an acute tip slightly ridged above. 



Length .70 — .85 inch. 



New Jersey, Pennsylvania and Illinois, (Coll. Ent. Soc. Phil.). 

 (Coll. Mr. Norton). 



The largest species known, easily identified by the dark violaceous 

 wings, black face and thorax, and the obsolete enclosure of the propo- 

 deum, while the abdomen is considerably stouter than usual. 



