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SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I39 



Early in the fourth instar of the larva paired thickenings of the epi- 

 dermis appear behind the region of the ninth sternum. These "genital 

 plaques" soon take on the form of budlike outgrowths, which are the 

 primary phallic lobes (fig. 28 A, PhL). With further development 

 the lobes elongate and unite at their bases, forming the genital ap- 



Bmr 



Tmr 



Fig. 28. — External genital organs of the adult male, and their development. 

 (A,B,C, from Christophers, 1922.) 



A, The primary phallic lobes that appear in a late instar larva behind the 

 sternal region of the ninth abdominal segment. B, Later stage of same, each 

 primary lobe divided into a mesomere and a paramere. C, Still later stage, 

 mesomeres united around the gonopore to form the aedeagus. D, Adult genital 

 apparatus of Anopheles quadrimaculatus, lower surface (dorsal). E, Parameres 

 and claspettes of Aedes pullatus. 



Aed, aedeagus; Bmr, basimere; bp, basal plate; clsp, claspette; Gpr, gonopore; 

 I XT, ninth abdominal tergum; Mmr, mesomere; PhL, primary phallic lobes; 

 Pmr, paramere; Tmr, telomere. 



pendages as they appear in the pupa (fig. 16 F). At this stage the 

 lobes are termed "proandropodites" by Christophers (1922), but this 

 term literally translated would mean "primitive male parts of legs" 

 (as "coxopodite" means the "coxal part of a leg"). Since there is 

 no real evidence that the male genital organs of insects represent 

 primitive legs, the genital organs of the pupa are simply the developed 

 phallic lobes. Within them are formed the definitive genitalia of the 



