1840.] 



Himalayas and of India. 



107 



height and dh'ection of its mountain ranges promoting or checking radia- 

 tion, its mighty rivers and interminable jungles, its soil, strata, and arid 

 deserts, absorbing and radiating heat, exert their varied influences, and 

 modify the temperature of that extensive Continent; and yet, admitting 

 thus much, I cannot help stating an opinion, that according to the extent 

 of the country, no other portion of the globe enjoys a more general and 

 equable uniformity of temperature than India. This may satisfactorily 

 be proved, provided we take as the basis of our argument the wide range 

 of region, over which not individual species, but whole genera of Insects 

 extend, and the general uniformity of Oriental vegetation. Before dis- 

 missing the important subject of temperature, I wish to offer a few re- 

 marks on the variation of heat and cold throughout the summers and 

 winters in the Himalayas and in India. In the former Dr, Royle states, 

 in his admirable pages, that the Flora of the Himalayas in the spring 

 and summer of the year resembles that of Europe, while in the rainy 

 season it becomes intermixed with tropic-like vegetation ; and hence 

 there is a certain admixture of genera belonging to temperate and tro- 

 pical climes. The change of temperature and of moisture producing a 

 new vegetation, exercises a corresponding influence over the distribution 

 of Insects throughout the same country ; and consequently we have 

 reason to expect, as will afterwards appear in my remarks, that its ento- 

 mological character is also twofold, uniting in itself that of both zones. 

 This intermingling of genera of tropical and temperate regions will ever 

 probably be found more perceptible in the rainy season, in advancing from 

 the valley to the mountain height ; and perhaps we ought to know the 

 results of the following researches, before we attempt to arrive at any 

 conclusion respecting the distribution of animal groups in the Himalayas 

 or in India. I would therefore suggest to future travellers in these mag- 

 nificent regions, first, to endeavour to ascertain the differences of climate, 

 and the cau ses which affect its temperature ; secondly, to find out the 

 average limit to which tropical forms extend, to state where they most 

 abound, where begin to lessen, and finally terminate; thirdly, to note 

 in what proportions the genera of tropical and temperate climes are in- 

 termingled ; fourthly, at what altitude temperate forms predominate 

 over tropical ; and, lastly, to mention as nearly as it is possible the 

 range of any group of animals in preference to that of any in- 

 dividual species : both objects, however, are desirable. In addition 

 to the above desiderata, it will be necessary to note the seasons of 

 Insects and times of their appearance, the soil in which they are found, 

 and the vegetation upon which they live ; since the distribution of 

 animals in general is greatly dependent on food, which food will abound, 



