560 The University Science Bulletin. 



apex. These plates, as is shown from nymphal development, arise 

 from a genital area on the ninth segment. They are indistinctly 

 fused with the caudoventral margin of the pygofer or with the area 

 termed by Crampton (1922) the hypandrium. The lateral margins 

 of the hypandrimn are indistinguishably united with the lateral 

 margins of the pygofer. The plates are separated along their mesal 

 lines by a long cleft which extends nearly to the eighth sternite. 



The styles (pi. LXI, figs. 7 and 8) have been given various names, 

 such as gonistyli, claspers, or genital styli. They are very irregular 

 in shape. At their cephalic end they taper to a very slender point, 

 while their caudal end is truncate. The widest part of the style is 

 at the point of attachment to the connective. Just cephalad and 

 caudad of this point it is constricted, but it broadens out again 

 caudad of the latter constriction into a second enlarged part. At 

 this particular point on the dorsal surface of each clasper arises a 

 prominent hook, the tip of which extends in a cephalomesal direc- 

 tion. From a lateral view of the genitalia (pi. LXI, fig. 5) the 

 nature of the relation of this hook to the style can best be seen. 

 Just distad of each hook is a slight notch in the clasper. The apex 

 of the organ bends mesad in a distinct cur^•e. The styli are con- 

 nected to the ventral wall of the pygofer at about the laterocephalic 

 angles of the hypandrium. and they extend directly caudad. They 

 are fastened to the connective only at its extreme lateral tip by a 

 very narrow band of membrane, although the connection would seem 

 to be much greater, since from a ventral view of the organs the con- 

 nective covers a large part of the claspers on each side. The union 

 of the two can be seen from a ventral and lateral view of the 

 genitalia. The styli are fairly well chitinized, but not enough to 

 keep them from being flexible. Their function is that of clasping 

 or interlocking during copulation. 



The connective (pi. LXI, figs. 7 and 8) is a flat ehitinous plate, 

 roughly triangular in shape, which extends between the two claspers 

 and is attached to the latter at about the base of their anterior third. 

 The lateral margins are produced into a slender recurved hook which 

 extends cephalad and wdiose inner margin is attached to the styli. 

 The broad basal part of the connective is chitinized, but the apical 

 region is entirely membranous. Bordering this membrane on the 

 sides are two slender, ehitinous rods which extend caudad, where 

 their tapering points are attached to the ventral surface of the base 

 of the oedagus. It has been suggested by Doctor Lawson that the 

 connective may possibly represent the tenth sternite, since its origin 

 has not otherwise been accounted for. 



