Temperature Experiments on tioo Tropical Butterflies. 455 



I am doubtful as to this interpretation. In the ex- 

 tremely hot dry weather of the desert, the butterfly, like 

 the majority of other insects, altogether disappears ; birds 

 shift their quarters ; and reptiles and predatory insects 

 become scarce. During the short rainy season, or, for 

 that matter, after a few showers, insect and other life 

 becomes very abundant for a short time, during which I 

 doubt there being a greater struggle for existence than in 

 other places where the type is found. Insects, though 

 few in species, are particularly numerous in individuals, the 

 members of the genus Teracolus, for instance, are frequently 

 excessively common. 



If tlorippus is a desert form particularly fitted for such a 

 life, we should expect it to be dominant in the Punjab,* 

 Bikanir, and Rajputana deserts, where, if it occurs at all 

 in the latter places, it is exceedingly rare, though the type 

 is common enough. We should also expect it to be com- 

 mon on the hot dry plains of Mashonaland and other 

 similar localities south of the Zambesi, but on the contrary, 

 it is very rare, though the type is abundant. 



Again, presuming that it is a later form, it is difficult 

 to account for the absence of intermediates. The accepted 

 interpretation would be, I presume, that they are not so 

 fitted for a desert life. If this be so, we must assume an 

 esthetic eye for small differences in colour and pattern, on 

 the part of birds and other enemies, for which the evidence 

 is at present deficient. 



I hold the view that the sporadic character of much 

 of its distribution, the production by artificial means of 

 intermediates, and that it lias been bred from chrysippus, 

 clearly show that it is the ancestral form ; and though we 

 are ignorant as to its origin, and the nature of its evolu- 

 tion, the proof that it has been guided by Natural Selection 

 has not been satisfactorily demonstrated. 



I), chrysippus form alcippus. 



Prof. Poulton, in the above mentioned work, considers 

 that the white hind wings of the form alcippus have been 

 developed on the West Coast of Africa, where in some 

 localities it is dominant, to give it greater conspicuous- 

 ness where there is abundance of food, and thus warn 



* Colonel Yerbury took two or three specimens at Campbellpore, 

 in the north of the Punjab. They are now in the National Collection. 



TRANS. ENT: SOC. LOND. 1912. — PART II. (OCT.) 11 H 



