1885.] L. dc ^^iccyillc— List of the Butterflies of Calcutta. SO 





Pr. 



cssnro. 



Vapoui 



■ Tension. 



September 





•341 in. 





•779 in. 



October 





•646 





•4G4 



November 





•669 





•335 



December 





•709 





•268 



By inserting these figures and those for dust above given in the 

 formula, log ]j = b log a -^ f log (S -\- d log y, it is found that the most 

 probable values of the constants are : — 



a = -99518 



P = -78091 



7 = -98924 

 These results, while confirming those already arrived at, indicate 

 that the absorption of solar radiation by dry air is greater than I have 

 hitherto supposed, though not nearly bo great as the absorption by water 

 vapour. 



IV. — List of the Butterflies of Calcutta and its Neighhourliood, ivith Notes 

 on Habits, Food-]jlants, 8fc. — By Lionel de Nice'ville. 



[Received ISth October ; — Eead 3rd December, 1884.] 



In the ' Entomologist's Monthly Magazine,' 1882 vol. XIX, p. 33, 

 there is a paper by Mr. G. A. J. Rothney, entitled, " A list of the 

 Butterflies captured in Barrackpore Park during the months of Septem- 

 ber, 1880, to August, 1881." In this list, however, only 98 species 

 are mentioned, which probably all occur in Calcutta, the two places 

 being but 14 miles apart, and both situated on the low-lying deltaic banks 

 of the Hughli. I have accordingly included all those of Mr. Rothney's 

 species which I have not myself met with in Calcutta, distinguishino" 

 them by an asterisk prefixed to the serial number. 



One of the most interesting points to which my attention has been 

 drawn in these butterflies is the occurrence of seasonal dimorphism, 

 there being in several species an ocellated form which occurs only in 

 the rains, the cold and dry seasonal being non-ocellated. The constancy 

 of this phenomenon is such that I cannot help thinking there must be 

 some physical reason for it, can it be a protective one ? The difference in 

 the garb of the surrounding vegetation makes it little remarkable that a 

 change should be found in the coloration of the butterflies of the two 

 seasons, but it is difficult to see why this change should show itself in 

 the obliteration or development of ocelli. The only hypothesis which I 

 can suggest is, that during the rains the density of the vegetation is such 



