NO. 8 INSECT ABDOMEN — -SNODGRASS 83 



of the first valviila are produced in the usual manner by muscles of the 

 first valvifer arising on the eighth tergum. 



The ninth segment has a large tergal plate (fig. 26, A, B, IXT) 

 covering the back and sides of the segment ; its anterior ventral angles 

 are extended anteriorly within the seventh segment, and, as just noted, 

 they are here fused v^ith the basal plates of the inner rami of the 

 first valvulae (D). Below each lateral margin of the ninth tergum 

 is an elongate lobe (B, 2Vlf), the outer wall of which is not con- 

 tinuously sclerotized, but presents a dorsal and a ventral plate (E, 

 a, b). The lobe, however, is unquestionably the second valvifer 

 (2Vlf), since it carries the second and the third valvulae 

 (2VI, sVl). The second valvula is attached to the anterior end 

 of the second valvifer by an arcuate basal ramus {rsvl), which 

 slides on the concave margin of the inner ramus of the first valvula. 

 The large third valvula (3VI) arises from the distal end of the second 

 valvifer ; the third valvulae form two broad free lobes embracing the 

 distal end of the shaft of the ovipositor between their concave mesal 

 surfaces. The second valvifer is articulated at a point near the middle 

 of its dorsal margin to the lower edge of the ninth tergum, and mus- 

 cles arising on the latter, inserted anteriorly and posteriorly on the 

 valvifer, rock the latter up and down and impart a back-and- forth 

 movement to the second valvula attached to its anterior end. The 

 two second valvulae probably work in unison because of their con- 

 nection with each other. The true sternal region, or venter, of the 

 ninth segment is the narrow membranous wall between the two second 

 valvifers. 



According to the terminology used by Ekblom (1926, 1930) for 

 naming the parts of the hemipterous ovipositor, the dorsal plate of the 

 second valvifer (fig. 26 E, b) is the " parasternite " of the ninth 

 segment; the small ventral plate (a) supporting the third valvula 

 is " sternite a " of the ninth segment ; and the third valvula is 

 " sternite b " of the ninth segment. 



The shaft of the ovipositor of Penfacora is formed of the first and 

 second valvulae, the first being external, the second internal. Each 

 first valvula consists of a strong outer part (fig. 26 C, iVl) with coarse 

 teeth on the upper margin of its distal part, and of an inner mem- 

 branous fold. Basally, as already observed, the first valvula is con- 

 nected externally with the lower angle of the first valvifer (C, c), 

 and mesally by an arcuate inner ramus with the lower anterior angle of 

 the ninth tergum (D). The second, or inner, valvulae (E, 2VI) are 

 united with each other for most of their length by a narrow mem- 

 brane between their dorsal margins ; their distal parts, however, are 



