30 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 



the first pair are free processes. The length and shape of the ovi- 

 positor vary somewhat in different Thysanura ; in Machilis (fig. 6 A) 

 the distal part of the organ is abruptly bent upv^ard. 



The morphological origin of the gonapophyses cannot be deter- 

 mined from the evidence at hand. The structures are treated in this 

 paper as being processes of the gonopod bases having the nature of 

 endite lobes. Some writers prefer to regard them as the true telopo- 

 dites of the genital appendages, but their limitation to the gonopods, 

 their origins from the proximal parts of the latter, their special func- 



Mb 



smcl 



^m 



VIllLB 



cl ermcL 



Mb 



Sty smcl 



r~iVl(lGor>) 



Fig. 7. — Female gonopods of Ncsomachilis maoriciis, dorsal view. 

 Note in each appendage muscles from basal plate to stylus (smcl) and to 

 gonapophysis (gmcl). 



tion, and the fact that they never show a leglike form seem to be sug- 

 gestive, rather, that the gonapophyses are secondary structures de- 

 veloped on the appendages of the eighth and ninth abdominal seg- 

 ments in adaptation to the special function these appendages have 

 assumed. 



The bases of the thysanuran gonopods, in conformity with the bases 

 of the pregenital appendages, are well equipped with muscles arising 

 on the terga of their respective segments (fig. 6F). Some of these 

 muscles of each appendage are inserted on the plate forming the ven- 

 tral wall of the limb basis, and others at the inner margin of its 

 membranous dorsal wall. Smaller groups of median, longitudinal 



