THE STYLES AND GENITAL CLASPERS 



177 



tera, Lepidoptera, Diptera, and certain phytophagous Hymenoptera. 

 They do not appear to occur in insects which are provided with an 

 ovipositor. In Thysanura the A 



styles are present on segments 

 1-9 (Fig. 179). Those of the 

 male Ephemeridae, of which 

 there are two pairs arising from 

 the ninth segment, are remark- 

 able, since they are jointed, and 

 they serve to represent or may 

 be the homologues of two of the 

 pairs of stylets composing the 

 ovipositor of insects of other 

 orders. The lower pair (Fig. 

 197, rh) are either 2-, 3-, or 

 4-jointed (in Oniscigaster 5- 

 jointed), while those of the 

 upper pair are 2-jointed (rh'). 

 These rhabdopods in the ephem- 

 erids are evidently very prim- 

 itive structures, since they 

 approach nearest in shape and 

 in being jointed to the abdom- 

 inal legs of Scolopendrella and 

 the Myriopoda. The styles of 

 the Orthoptera are survivals 

 of the embryonic appendages of F[G 197 _ AMomen of Ellhemera (Lcpto . 



the ninth seo-niPllt fWheelpr pblebia) cupida, $: c, base of cercopoda; rh, 



-^ outer 8-jointed daspers or rhabdopods ; rh' , inner 



etc.). In Mantis they are seen i' air - A > side view - 



to have the same relations as the cerci, 

 as shown by Heymons (Fig. 200). 



In the Phasmidoi, in Anabrus, and in 

 the Odonata the cercopods, which are not 

 jointed, are converted into claspers, and 

 in the Odonata the claspers are spiny 

 within, so as to give a firmer hold. The 

 suranal plate is apparently so modified as 

 to aid in grasping the female. In nearly 

 all the Trichoptera there are, besides the 

 suranal plate, which is sometimes forked 

 FIG. 198. End of abdomen of (Nosopus), a pair of superior and of 



Corydalus cornutus, rf : rh. rhabdo- -, 



pod ; c, cercopod. interior claspers, and in certain genera 



