33 



series of dardanus forms, and place in the frame the drawers 

 representing the subspecies tihidlus, which extends from the 

 Escarpment to the east coast and spreads southwards till it 

 insensibly passes into the south-eastern and southern subspecies 

 cenea. The male tibullus is characterised by heavy black mark- 

 ings, especially on the hindwing. It may be interesting to those 

 who look on climatic conditions as the causes of variation to note 

 that the hippocoon form of the east coast, with its drier climate, 

 shows a reduction in the black markings as compared with the 

 same mimetic form on the moister west coast, but that the 

 males, on the contrary, are far more heavily marked with black 

 on the east coast than on the west ! If therefore climatic con- 

 ditions are of any avail in the production of these patterns, it 

 is obvious they have wrought opposite effects on the two sexes of 

 dardanus. 



It is interesting to pause for a moment and compare the 

 development of the black markings of the male subspecies of 

 dardanus. These markings are least developed in the north- 

 eastern antinorii, moderately developed and to much the same 

 extent in the Madagascar meriones, the Nairobi polytrophus and 

 the western dardanus, by far the heaviest in the Eastern tibullus. 

 As we pass southward into cenea the markings again become 

 less heavy, in some individuals indeed approaching those of 

 the west-coast males. Nevertheless, as a whole, cenea is more 

 heavily marked with black than any other subspecies except 

 tibullus. 



The ñrst two drawers exhibit tibullus from Nairobi to the 

 British East African coast, and southward into German East 

 Africa. Hippocoon is still seen to be by far the commonest form. 

 The single trimeni from Zanzibar, already referred to (see p. 28), 

 is to be found in one of the drawers. Trophonius and cenea are 

 both present, in correspondence with their models, while the 

 second drawer contains the single remarkable planemoides from 

 the Mombasa district (see p. 28). 



The next two drawers now placed in the frame represent an 

 exceedingly fine collection from a little patch of primitive forest 

 on Mount Chirinda (3,800 ft.) in S.E. Rhodesia, close to the 

 Portuguese border, a tract of country formerly knowTi as Gaza- 

 land. From this locality, owing to the kindness of my friends 



5 



