J. H. MERRILL 123 



and ninth segments are for the most part membranous. The 

 base of the sheaths of the ovipositor arises in these ventral 

 plates and extends thus nearly to the apex of the abdomen. 

 Near the apex comes a decided break where the sheaths proper 

 are articulated. These are long and slender, equalling the ovi- 

 positor in length. They are concaved inwardly and convex 

 with ridged rings outwardly. The nota of the eighth and ninth 

 segments are small, but their pleura extend backward and are 

 overlapped and partially concealed by those of the seventh 

 segment. On the apex of the ninth segment is a small, blunt, 

 rod-like projection, and beneath on either side of the groove 

 which receives the sheaths is a small cercus. Both of these 

 parts are probably tactile in their nature. 



Sex Distinction 



The presence or absence of the ovipositor anil its sheaths is 

 the most readily noticed sex distinction, but there are others 

 not so easily noticed. The sternal plates of the female are longi- 

 tudinally divided and the small projections described above 

 are usually present, while in the males, the sternal plates are 

 entire and the projections are absent. The abdomen of the 

 female increases in size towards its apex while that of the male 

 is long, slender, and approximately of the same width throughout. 

 The small rod-like projections on the ninth segment of the female 

 are, of course, lacking in the male, their positions being occupied 

 by the male external genital organ. The ventral cerci of the 

 female are absent in the male but the male has a pair of small 

 cerci on the dorsal apex of the eighth segment which are not 

 found in the female. 



Classification 



Tribe Pimplini 



Ashmead, Proc. Ent. Soc. Wash., iii, p. 278, (1895). 

 Schmiedeknecht, Genera Insectorum, 62nd fascicle, p. 18, (1907). 



On May 3, 1895, Ashmead read a paper before the Entomolog- 

 ical Society of Washington, which was later published in the 

 Proceedings of that society, in which he proposed the breaking 

 up of the sub-family Pitnplinae into a number of tribes, one of 

 which was to be called Pimplini. 



TRANS. AM. ENT. SOC, XLI. 



