434 Dr. A. S. Packard, Jr's Revision of the 



B. Abdominal fascia; remote ; tip of abdomen red. 

 Species large, scutellum with two quadrant-shaped yel- 

 low sp>ts 0. laetus. Say. 



Two terminal rings of abdomen red 0. analis. Cress. 



Appendages to the meta-scutellum oval 0. emarginatus, Say. 



C. Tip of abdomen black. 



Fore tibiae red in front ; legs black, appendages to meta- 

 scutellum small, sinuate, mucronate 0. interruptus, Cress. 



Very small, propodeum finely lineated, no distinct trian- 

 gular area 0. parvus, Cress. 



Spine undivided, propodeum lineated, not ridged on the 



sides: abdomen coarsely punctured mucronatus. Pack. 



Body coarsely punctured: propodeum rugose 0. 4-notatus. Say. 



Section A. 

 Oxybelus similis. Cress. 



0. similis. Cress., Proc. iv. p. 476. (1865). 



Colorado Territory, (Ridings, Coll. Ent. Soc. Phil.). 



Section B. 

 Oxybelus laetus. Say. 



0. laetus, Say, Bost. Jour. Xat. Hist., i. p. 375. (1837). 



Smith, Cat. Hym. B. M. iv. p. 390. (1856). 



$ . Front rather narrow, spreading out at the insertion of the an- 

 tennae; vertex more elevated and convex than in 0. mucronatus. not 

 so finely punctured and more polished; a thin pubescence in front, 

 mandibles fuscous, black at tip; antennae pale reddish, 2d joint of 

 scape blackish, reddish at each end; prothorax smooth above, well 

 cariuated, distinctly angulated on the sides ; yellow on each side. 

 Thorax thickly but not very coarsely punctured, shining ; two quad- 

 rant-shaped yellow spots on the scutellum, two flattened horizontal 

 mucronate spines connected by a thin testaceous membrane on the 

 meta-scutellum, and two curved parallel lines of membrane going to 

 the insertion of the hind wings. Propodeum with the basal spine as 

 usual, no diverging lines, but broad polygonal fossae instead; sides 

 striated, bounded externally by a high prominent ridge beyond which 

 the flanks are densely and evenly striated; posteriorly in the apex of 

 the v-shaped space the striae are nearly obsolete. Tegulae testaceous; 

 veins ferruginous ; legs deep black, anterior tibiae reddish ; tarsi 

 brown, uuguinal joint reddish; middle and posterior tarsi black-brown; 

 tibiae very stout and thick, not so heavily spined as in 0. mucronatus. 

 Abdomen very short and thick, cordate-triangular, scarcely longer than 

 the thorax alone, with the usual yellow spots, those posterior to the 

 tir-t being sub-geminate ; tip broad spatulate, broader than usual, red. 



Length, .32 inch. 



