90 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 89 



valvula has a single basal ramus (fig. 28 D, r2vl), which is attached 

 to the anterior end of the second valvifer {sVlf), and lies against 

 the concave margin of the inner ramus of the first valvifer (fig. 

 29 A). 



The first valvifer (fig. 28 B, iVlf) is a triangular plate attached 

 posteriorly by membrane to the anterior margin of the paratergite 

 {pt) of the eighth segment, and ankylosed with the lower anterior 

 part of the ninth tergum (IXT). In the normal position it is con- 

 cealed by invagination within the seventh segment (A). The inter- 

 segmental membrane between the seventh and eighth segments (B, 

 Mb), therefore, extends forward from the lower end of the eighth 

 tergum along the dorsal margin of the valvifer to the rudimentary 

 eighth sternum (VlllSfn) beneath the anterior ends of the valvifers. 

 To the anterior end of each first valvifer is flexibly attached the outer 

 ramus of the first valvula (figs. 28 B, C, 29 A, B, rivlo) ; the inner 

 ramus of this valvula (figs. 28 C, 29 B, rivli), as already noted, is 

 firmly attached by a small plate (m) to the lower anterior angle (n) 

 of the ninth tergum, mesad of the first valvula. A muscle arising 

 on the eighth tergum (fig. 28 B, j) is inserted on the dorsal margin 

 of the first valvifer (fig. 29 B, j). The first valvifers are not 

 freely movable because of their posterior ankyloses with the ninth 

 tergum, but they are flexible, and the contraction of their muscles 

 evidently must elevate their anterior ends and produce a depression 

 of the distal part of the ovipositor. A pair of short thick muscles 

 attached laterally on the valvifers and internally on the mesal plates 

 of the inner rami of the first valvulae, are probably antagonistic 

 to the dorsal muscles of the valvifers. 



The second valvifer (fig. 28 D, 2Vlf) is a strong, elongate sclerite 

 having the ramus of the second valvula {2VI) attached to its anterior 

 end, and the base of the third valvula (3VI) movably articulated 

 to its posterior end. In the normal position the second valvifer is 

 mostly concealed, in a lateral view (A), by the first valvifer. The 

 second valvifer is movably articulated at a point somewhat beyond 

 the middle of its dorsal margin to a condyle (D, p) on the lower 

 end of a strong anterior ridge (r) of the inner surface of the ninth 

 tergum (C, IXT). Two large antagonistic muscles arising on the 

 ninth tergum (figs. 28 D, 29 A, 6, 7) are inserted on the opposite 

 ends of the second valvifer {bVIj). These muscles evidently rock 

 the valvifer up and down on the fulcrum of the ninth tergum, and 

 thus impart a strong back-and-forth movement to the second valvula 

 attached by its narrow basal ramus (fig. 28 D, r2vl) to the anterior 

 end of the valvifer. The second valvulae slide freely on their tracklike 



