112 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 89 



ponding first valvifer (iVlf). The proximal ends of the united second 

 valvulae (D, E, 2VI) present two lateral swellings which abut against 

 the anterior ends of the second valvifers, but from each a narrow 

 ramus (D, r2vl) curves upward and posteriorly against the inner face 

 of the ramus of the first valvula of the same side, and is broadly 

 attached to a proximal dorsal lobe of the second valvifer {2Vlf). 



The first valvifer is a small plate (fig. 36 E, iVlf) articulating be- 

 tween the anterior ventral angle of the ninth tergum (a) and the 

 dorsal margin of the second valvifer (&) ; it gives attachment to the 

 ramus of the first valvula (rivl) by its upper margin (c). The lateral 

 part of the ninth tergum (IXT) has the form of a sclerotic fold, the 

 outer wall of which is deeply emarginate where the wide interseg- 

 mental membrane behind the eighth tergum is attached to it. 



The second valvifer is a large, elongate plate (fig. 36 E, 2Vlf), 

 overlapped by the lower angle of the ninth tergum, but, as in Pteron- 

 idea and other Hymenoptera, having no articulation or specific point 

 of movement on the latter ; it rocks on the ventral pivot (&) of the first 

 valvifer. The anterior end of the second valvifer is expanded in a 

 dorsal lobe (D) to which the ramus of the second valvula (r2vl) is 

 attached. Posteriorly the second valvifer bears the long, slender third 

 valvula (E, 3VI). 



The mechanism of the braconid ovipositor is the same as that of 

 Pferonidea. 



MEGARHYSSA ATRATA (PABRICIUS) 



The species of the ichneumonid genus Megarhyssa are remark- 

 able for the great length of the bristlelike ovipositor, which they 

 insert into dead wood of trees in order to deposit their eggs in the 

 burrows of wood-boring larvae on which their own larvae are 

 parasitic. 



The end of the abdomen of Megarhyssa is greatly enlarged and 

 curiously modified (fig. 37 A). The modification involves the seventh, 

 eighth, and ninth segments. The seventh segment is abruptly ex- 

 panded from the end of the sixth ; its sternum ( VII S) is turned 

 forward and projects downward beneath the anterior end of the 

 seventh tergum (VI IT). The eighth tergum {VII IT) lies behind 

 the seventh tergum, but its narrowed elongate, ventral ends are in- 

 flected within the lower parts of the seventh segment ; the eighth 

 sternum, as in other Hymenoptera, is completely obliterated. The 

 ninth tergum is concealed dorsally within the overlapping eighth 

 tergum, but its lateral parts are exposed ventrally (IXT) below 

 the eighth and seventh segments. When the ninth tergum is removed 



