174 



R. W. CROSSKEY 



305 



306 



307 



308 



Figs. 303-308. Showing characters of the larval hypostomium in genus Simulium (303 and 

 304) and characters of the genus Afrosimulium (305-308). 303, form of hypostomium in 

 subgenera in which rows of hypostomial setae lie parallel with lateral margins of hypo- 

 stomium. 304, form of hypostomium in subgenera in which rows of hypostomial setae 

 conspicuously diverge posteriorly from lateral margins of hypostomium. 305, maxillary 

 palp ($) in Afrosimulium. 306, second hind tarsal segment and apex of hind basitarsus in 

 Afrosimulium, showing deep pedisulcus and very reduced calcipala. 307, fore leg of 

 Afrosimulium, and tarsal claw of female. 308, <$ hypopygium of Afrosimulium. 



