198 The University Science Bulletin. 



DEVELOPMENT OF THE FEMALE GENITALIA. 



Ovipositor of Adult. 



(Plate XVIII. figs. 4-6.) 



In the female the genitaha also consist of three pairs of append- 

 ages. They are the ventral and dorsal pairs, which make up the 

 ovipositor proper, and the lateral pair, within which the ovipositor 

 is folded. The ventral pair arise from the eighth sternum, and the 

 dorsal and lateral pairs arise from the ninth sternum, the dorsal 

 pair from its cephalic margin and the lateral pair from its caudal 

 margin. 



The ventral valves arising from the eighth sternum are two long, 

 slender valves, tapering caudad and sharply pointed at the apices. 

 They are ventral in position and inclose the dorsal valves. The 

 ventral and dorsal valves of each side are joined one to the other 

 by a tongue-and-groove arrangement, the tongue being on the dor- 

 sal valve and the groove on the ventral. 



The dorsal valves are innermost of the three pairs and are dorsal 

 in location. They consist of a narrow, curved, rodlike base, and a 

 broader, flattened apical part which bears teeth along its dorsal 

 edge. The apex is sharply pointed and bears very fine teeth on 

 both dorsal and ventral edges. There are from seventeen to nine- 

 teen large teeth on the dorsal edge. 



The lateral valves are the outermost of the three and enfold the 

 other two pairs. They are broad, flat, and somewhat concave on 

 their inner surfaces. They are not capable of extension as are the 

 other two pairs, for in addition to being attached basally to the 

 ninth sternum, they are also attached to the pygofers for about one- 

 half their length. Their apical half is free. 



Nymphal Genital Appendages. 



(Plate XIX, figs. 1, 3, 5, 7, 9, 11.) 



In the first and second instars two pairs of very small chitinous 

 pockets may be seen, one projecting caudad from the eighth sternum 

 and the other from the ninth. In the first pair develop the ventral 

 valves of the adult ovipositor, and in the second the dorsal valves. 

 In these two instars the apices of the ventral pockets are at a dis- 

 tance from the bases of the dorsal pockets. The dorsal pockets, 

 extending caudad for about one-third the length of the ninth seg- 

 ment, are also short. 



In the third instar the ventral pockets have increased in length 

 and width. They are still short and broad. Their broadly rounded 



