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R. W. CROSSKEY 



241 



242 



243 



244 



245 



246 



247 



248 



neav 



249 



250 



251 



252 



253 



254 



255 



Figs. 241-256. Outline ventral views of shape of larval head capsule in African Simulium 

 showing range of form of postgenal cleft in subgenera and species-groups. 241, Eusimul- 

 ium, latipes-group. 242-244, Eusimulium, ruficorne-group. 245, Eusimulium, loutet- 

 ewse-group. 246, Pomeroyellum, alcocki-gr oup. 247, Pomeroyellum, bequaerti-gvoup. 

 248, Pomeroyellum, cervicornutum-group. 249, Pomeroyellum, kenyae-group. 250, Meil- 

 loniellum. 251, Lewisellum. 252, Phoretomyia. 253, Anasolen. 254, Freemanellum. 

 255, Xenosimulium. 256, Wilhelmia. 



