I20 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 85 



endite lobes of the gnathal appendages, and, as the latter, they some- 

 times occur in duplicate on each appendage. 



The gonapophyses are hollow, median outgrowths of the bases of 

 the gonopods, developed in both male and female insects during 

 postembryonic stages. They are movable by muscles arising in the 

 limb bases, or in areas of the genital segments derived from the latter, 

 except where they are operated by the segmental muscles of the body. 

 Theoretically the gonapophyses may be supposed to be either the 

 telopodites (endopodites) of the gonopods, or endite lobes of the 

 bases of these appendages. There are several objections to the first 

 view. The gonapophyses, for example, are never truly segmented, and 

 never have a form suggestive of a leg structure; they occur only 

 on the appendages of the genital segments, unless the cylindrical 

 processes of the first abdominal segment in certain Dicellura are 

 homologous structures; and finally, they serve only in a particular 

 capacity in connection with oviposition and copulation, except in 

 insects where they are secondarily adapted to form a stinging organ. 

 These facts, together with the invariable median position of the 

 gonapophyses on the gonopod bases, suggest that the gonapophyses 

 are basal endites of the gonopods, movable by muscles arising in the 

 basis, as such endites usually are, and specially adapted to the repro- 

 ductive functions. The genital apophyses might then be regarded as 

 serially homologous with the eversible or retractile vesicles of the 

 pregenital appendages and certain larval pygopods, in which case 

 Silvestri's idea that they represent " permanently everted eversible 

 vesicles " is better stated in the reverse, namely, that the eversible 

 vesicles are inverted gonapophyses. However, the vesicles do not 

 occur at points on the gonopod bases corresponding with the origins 

 of the gonapophyses, and the musculature of the two sets of organs 

 is characteristically different. It is perhaps possible that the gona- 

 pophyses are subcoxal endites, and the vesicles coxal endites. 



If none of the appendicular processes of the abdominal Hmbs can 

 be satisfactorily identified with the telopodite of a primitive appendage, 

 we must conclude that the abdominal telopodites have been lost from 

 all but the terminal segment, where they form the cerci, and that 

 the various persisting appendicular structures are accessory processes 

 of the limb bases. Otherwise, we must choose between the gona- 

 pophyses and the styli as possible representatives of the telopodites. 

 Of the two, the styli certainly present better credentials, considering 

 their occurrence on many segments of the abdomen as contrasted 

 with the segmental localization of the gonapophyses, their structural 

 and functional versatility by comparison with the limitations of the 



