APPENDIX. 335 



only yellow ; collar destitute of the yellow margin be- 

 hind. Smaller than the female. 



This species may readily be distinguished by the two 

 small, bright, yellow dots at tip each side of the metatho- 

 rax, and the bright colour of the posterior thighs. It varies 

 considerably in size. 



BEMBEX, Fabr. Panz. 



B, monodonta. Black; tergum with dilated, greenish- 

 yellow bands. 



Inhabits Pennsylvania. 



Front and vertex with cinereous hair ; labrum with a 

 greenish, oblong, margined spot each side, near the base ; 

 thorax hardly hairy; anterior edge, terminating in a spot 

 on the pleura; an oblique, abbreviated line above the 

 origin of the wings, terminating in a comma-formed 

 spot behind, greenish-yellow ; -tnetathorax, a transverse, 

 rectilinear line at base, and an arcuated one at base, slightly 

 interrupted in the middle, greenish-yellow; thighs, at tip, 

 tibiss and base of the tarsi, pale yellowish ; tips of the lat- 

 ter dusky; a dilated black line near the tip of the ante- 

 Fior tibiae; wings hyaline ; tergum with six yellow and green 

 bands, which occupy more than two-thirds of the surface ; 

 first band bilobate before, yellow, with a broad green poste- 

 rior margin; remaining bands somewhat dentated before; 

 the second and third bands yellow, with a green central 

 dash J fourth and fifth bands yellow, their anterior margins 

 green ; terminal band entirely yellow ; venter entirely 

 black; a single elevation on the second segment. 



Length % half an inch. 



In the collection of Mr. William W. Wood. 



