120 



W. Dohorty— A'o/ft* on Assam Biifterjliea. 



[No. 1, 



tionably distinct, must play a great part in such unstable races as those 

 of Terms. The results of Mr. de Niceville's previously mentioned experi- 

 ment with MelanUis (though not, I think, those of mine) may with 

 apparent justice be attributed by some to this cause. It is not by breeding 

 that species like those of Terias described by Mr. Moore from Mergui 

 will be invalidated. On examuiing the forms of dilfereut regions, one 

 observes that the genus varies similarly almost everywhere, that the 

 races have no well-marked habitat, aud that every fresh locality and 

 season adds links connecting them. The cutting down of forests seems 

 to j^roduce a general amalgamation of varieties which perhaps bred 

 truly before. Lvias is a much more variable genus in the scrub jungles 

 of Mount Abu, than in the high forests of Burma. In the open country 

 around Calcutta and Rangoon, there is an inconstancy in the specimens 

 of Terias which will rarely be found in the neighbouring tracts still left 

 in their original state. The plants these butterflies feed on, instead of 

 growing here and there in open spaces in the forest, are spread uniformly 

 over extensive districts, and the wandering habits thus originated load 

 to hybridism and the obliteration of local races. The varieties of 

 Teracolus, which are, so far as my experience goes, confined to diy, open 

 country, are by no means so locally true as those of the forest-haunting 

 genera. 



It was perhaps the general destruction of forests in the long-settled 

 parts of the East-India, China, Java — whether by the agency of nature 

 or by that of pi-ehistoric man, that gave rise to seasonal dimorphism 

 in the Satijrulce. In the wet, dark woodland, their ocelli served them as 

 a protection. Then came the change ; the country was partly deforested, 

 and, instead of the former uniformly damp climate, there was a long diy 

 season in which the rank vegetation withered, the sunlight entered 

 everywhere, and the ocellate butterflies were rendered conspicuous. 

 Some species disappeared from the regions thus affected, while others lost 

 their ocelli and assumed the angular shape and dull neutral colouring 

 of dry leaves, and so survived. In the less variable climate of the 

 equatorial regions, this has rarely taken place, and generally only the 

 oooUate broods are found there. And in desert regions, instances may 

 perhaps occur where the ocellate form has altogether disappeared. 



Other interesting examples of the effect of environment on insect 

 life may be mentioned. The large dark form of Hypolimnas holina 

 called jacinlJia occurs along with the typical race in many neigh- 

 bourhoods. But I have generally taken jacintha in shady jungle, 

 while the other variety may be common in the dry, open country half a 

 mile away. In Assam I observed a remarkable case of similar change 

 in the female of Appias Mppoides. The normal form is dark above and 



