INTRODUCTORY ESSAY. 95 



Bengal, the west coast of the Madras peninsula, and of Cey- 

 lon, contrast strongly with the drier parts of the intertropical 

 zone, and still more so with the loosely-timbered districts of 

 Central India, and of the base of the western Himalaya. 



sterile 



ins, which are 



mountain 



are 



timber 



immense 



Indian 



Nerbada, etc., are nowhere heavily timbered, but are gene- 

 rally absolutely destitute of forest, and extremely populous 

 and highly cultivated*. 



The tropical forests of India may be divided into those 

 which inhabit perennially humid districts, and those which 



sum 



mer rain and winter drought. 



The perennially humid forests are uniformly characterized 

 by the prevalence of Ferns, and, at elevations below 5000- 

 7000 feet, by the immense number of epiphytal Orchidea>, 

 Orontiacece, and Scitaminece : they contain a far greater 

 amount of species than the drier forests, and are further cha- 

 racterized by Zingiber acea, Xyridece, Palms, Pandanea, Dra- 

 caena, Piper, Chloranthas, Urticacea (especially Artocarpece and 

 Fici), Araliacea, Apocynece, shrubby Rubiacea, Aurantiacece, 

 Garciniacea, Anonacece, Nutmegs, and Dipterocarpete. < 



The drier tropical forests of the regions with contrasted 

 seasons, are much modified in luxuriance and extension by 

 the winter cold in those extratropical latitudes over which 

 they spread. In the chapter upon the meteorology of India, 

 it is shown that though the summer heat scarcelv decreases 



It is a much discussed question in India, whether the Gangetic plain was 

 ever covered with forest : the best authorities consider that it never was so ; but 

 there are others who hold the contrary opinion, and aver that the destruction 

 of the timber has produced a great change in the climate. The absence of vege- 

 table remains in the alluvium appears unfavourable to the lathr opinion. 



