NO. 8 INSECT ABDOMEN SNODGRASS 79 



(limb bases) supporting distally the short styH and basally the rudi- 

 ments of a pair of inner valvulae. In a winged adult female (Cramp- 

 ton, 1923) the three usual pairs of valvulae are well developed, but 

 the styli, present in the soldier form, apparently are lost. Below 

 the ovipositor the seventh sternum is produced as a subgenital plate, 

 or " hypogenum ", and the reduced eighth sternum forms a small 

 lobe beneath the base of the ovipositor. In other termites the ovipositor 

 is rudimentary or completely suppressed. Walker (1919) describes in 

 Termopsis a pair of small lobes arising from the eighth sternum, repre- 

 senting the ventral valvulae, but the valvulae of the ninth segment are 

 entirely absent. 



VI. THE OVIPOSITOR OF HEMIPTERA 



The genital segments and the ovipositor of the Hemiptera present 

 the following characteristic features : 



1. The shaft of the ovipositor is formed of the first and second 

 valvulae, the first being external and ventral, the second internal and 

 dorsal. The second valvulae are generally united with each other. 

 either for a part or for most of their length. 



2. The sternum of the seventh abdominal segment forms the sub- 

 genital plate of the female, and encloses a small vestibular chamber 

 at the base of the ovipositor. 



3. The eighth segment is exposed dorsally, but its lateral and ventral 

 parts are mostly concealed within the seventh segment. 



4. The first valvifers have a pleural position below the tergum on 

 the sides of the eighth segment, though their posterior angles may be 

 flexibly attached to the ninth tergum. The dorsal muscles of the first 

 valvifers arise on the eighth tergum. 



5. The sternum of the eighth segment is rudimentary, being repre- 

 sented generally by a mere fold of the integument below the base of 

 the ovipositor at the anterior end of the vestibulum. The genital 

 chamber is correspondingly reduced in most cases to a small pocket 

 beneath the gonopore ; in some of the Cicadidae, however, the genital 

 chamber forms a large pouch into which open the median oviduct 

 and the spermatheca. 



6. The first valvulae have each two proximal rami. The outer 

 ramus is flexibly attached to the ventral angle of the first valvif er ; the 

 inner ramus expands in a small plate solidly united with the anterior 

 ventral angle of the ninth tergum. A muscle extends from the inner 

 face of the first valvifer to the basal plate of the inner ramus. 



