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SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 85 



is usually reduced, and its tergal plate becomes small, or unites with 

 the epiproct. In certain cases, however, the tenth segment is developed 

 quite independently of any relation to the cerci, as in some of the 

 Homoptera, in which the cerci are rudimentary or absent. In the 

 cicada (fig. 8 C) the tenth tergum is a strong plate produced down- 

 ward on the sides into a pair of hooked lobes (/) embracing the distal 

 end of the aedeagus. 



XT 



VIIIS 



Fig. 8. — -Terminal abdominal structures of various insects. 



A, larva of plecopteron, ventral view, showing cerci, paraprocts, and epiproct 

 as parts of eleventh segment. B, Gryllus assimilis, dorsal view, showing union 

 of epiproct with tenth tergum. C, Magicicada scptoidccim, with eleventh seg- 

 ment distinct from tenth. D, Scaptcriscus didactylus, female. E, Diaphcrnmcra 

 jcmorata, male. F, female of same, showing paraprocts fused with tenth ster- 

 num. G, lateral view of genital and postgenital segments of female Diaphernincrn 

 jcmorata. showing ovipositor, and subgenital plate produced from eighth ster- 

 num. H, end of abdomen of female Paiwrpa coiisuctitdinis. 



True appendages are absent from the tenth segment in postem- 

 bryonic stages of all Apterygota and hemimetabolous Pterygota. 

 Rudiments of appendages, however, are well known to be present 

 on the tenth segment of many insect embryos (figs. 5 A, 9 A, XApd). 

 The idea that these appendages are developed in the female into the 

 third pair of valvulae of the ovipositor is now generally regarded as 

 erroneous, since it is clear that both the second and the third pairs 

 of valvulae are parts of the gonopods of the ninth segment. Rerlcse 

 (1906) records an anomaly found in an adult female of Locusta 



