VALIDITY OF SOME FORMS OF MIMICRY. 713 



attention being drawn by him to " its slow, lazy and almost 

 unwieldy flight," the chai'acteristics of an unpalatable buttei-fly. 

 It does not occur or very I'arely in the north of the island, where 

 a bird, the Paradise Flj^catcher, is very abundant, but at Kandy, 

 to which place every visitor goes, and whei'e possibly Dr. Doflein 

 made his observation, the butterfly is very common and the Vjird 

 rare, though T have seen it. But it so happens that at the foot of 

 the Nilgiris, both bird and buttei'fly inhabit the same disti'ict and 

 the former is an inveterate enemy of the latter, it eats numbers 

 of them b}'^ nipping off" the wings and swallowing the body. The 

 slow, lazy flight may possibly advertise its unpalatability to some 

 birds, but it makes it the easier victim to the Paradise Flycatcher, 

 which in my opinion is the greatest enemy butterflies have in 

 this part of the world. 



I have always experienced considerable difficulty in under- 

 standing how a distasteful butterfly has acquired a slow sailing 

 flight *. It is easy to see how swift flight could be brought about 

 by natural selection, but the converse is not so clear. Presumably 

 Euploeas, Danaines, etc., have always been distasteful on account 

 of the poisonous or nauseous nature of the food-plants, and those of 

 slower flight, as in the case of the palatable kinds, would naturally 

 be first captured, and we can understand how a race of quickly- 

 flying evil-tasting butterflies would be evolved by natural selection. 

 But if quick flight is of assistance in enabling a tasty butterfly 

 to escape capture, I find it difficult to l:)elieve that a nasty one, 

 with equal powers of flight, would not be equally benefited. And 

 if this be so, slow flight foi- the purpose of advertising unsaleable 

 goods seems unnecessary and the method by which it has been 

 evolved veiy obscure. 



When we come to study fast-flying butterflies in their native 

 haunts, we find in eveiy case a diflferent rate of flight according 

 to the hour and weather. If it is a cloudy morning they fly much 

 slower than they do in hot bright sunshine ; the majority fly 

 their fastest aftei' 10 a.m. till 3 p.m., often i-esting between 12 

 and 2. But in the early morning and late afternoon, these same 

 butterflies can often be captured with the gi'eatest ease, as at this 

 time they are usually feeding. This is the case with the rapidly 

 flying Teracolus {fausta, danae, &c.) and many Papilios, and this 

 may account for the difiei-ent opinion Dr. Doflein and I hold 

 regarding P. hector and P. polytes. He considers them to be of 

 swift flight, and so no doubt they are in the middle of the day, 

 and particulai-ly when flying ovei- bare gi^ound from one patch of 

 cultivation to another ; but on a dull day or early in the morning 

 or evening they are particularly easy to catch. If Dr. Doflein is 

 correct we have here an instance of a Miillerian combination of 



* Mr. Marshall speaks of " the acquisition of unpalatability," by which I presume 

 he means that a slightly nauseous butterfly has become more so by a process of 

 evolution, and this has been accompanied by an increasingly slower flight. There 

 is no proof, so far as I know, that a JSupIcea for instance has undergone any such 

 process, and the assumption appears to be entirely theoretical. 



