116 GENERA OF HYMENOPTERA. 



Anterior winpt with a distinct sinus between the marginal and third sub- 

 marginal cells. 



Second snhniarginal cell snbtri angular, much narrowed towards the 

 marginal : lahrum twice as long iis broad, not swollen at base ; man- 

 dibles slender, unarmed ; maxillte, when folded, concealed by the 

 labrum Microbenibex Patton. 



Second submarginal cell subquadrate, not or very slightly narrowed 

 towards the marginal ; labrum not twice as long as broad, swollen 

 at base; mandibles armed with a tooth; maxilla;, when folded, ex- 

 tending beyond the raesothorax Steulolia Say. 



Maxillary palpi loug, slender; anterior wings with a distinct sinu.s between 

 the marginal and third submarginal cells Moiicdulu Latr. 



To the genus Sphecbis belong tAvo large species, which have been 

 generally referred to Stizus; one of them, speciottits, — an exceedingly 

 variable species found all over the United States — preys upon the 

 Cicada, with whidi it provisions its nest ; an interesting account of 

 the habits of this species is given by Fuller in the " American En- 

 tomologist," vol. iii, p. 167. Megastizim has one species from the 

 Western States and Texas, and Bembecinus two from Florida and 

 Texas. To StiznA two sj)ecies are referred, one of which, Servillei 

 St. Farg., ha.'^ not yet been identified, while the other, tmieinctus Say, 

 is very common in the far AVest and Southwest ; it is black with a 

 broad reddish band on the abdomen, and the wings broad, violaceous- 

 black, with the extreme tips subhyaline. 



The Bembecini have not yet been monographed, and considerable 

 confusion exists in the species belonging to the genera Bembex and 

 Monedula, of which seven are referred to the former and nine to the 

 latter, while Microbembex and StenioUa have each one sj)ecies. 



Family NYSSONID^. 



Since the publication of Dr. Packard's " Revision of the Fossorial 

 Hymenoptera" (Proc. Ent. Soc. Phil, vi, 1866-67), in which this 

 family was reviewed, nothing has been done in the study of our 

 species, except those belonging to Nymon and allied genera, which 

 have been noticed in a pajwr published in the ninth volume of these 

 Transactions, 1882. 



The genera are readily separated by the characters given below. 



Table of Genera. 



Second submarginal cell not petiolate 2. 



Second submarginal cell petiolate 3. 



