KE^V COLONIAL FLORAS. 61 



consequently of climate. Instances occur, as in the genera Hortonia, 

 Mappia, Turpinia, Mwnt/mus, Elceodendron, in wliicli a more elevated 

 locality produces a form or variety possessing a stouter habit and 

 larger flower than are observed in the same species -when growing 

 only a little above the level of the sea. These forms or varieties 

 would probably be viewed by some botanists in the light of distinct 

 though closely allied species, and they occupy, in fact, that debatable 

 ground the difficulties and perplexities of which the practical natural- 

 ist alone knows, and which, in the opinion of many (and I may include 

 myself among the number), are only to be got rid of by the adoption 

 of the views enunciated by Mr. Darwin as regards the relationship 

 of alKed forms or species by descent from a common ancestor." 



Owing partly to our ignorance of the extent of the Moras of 

 other tropical islands, and partly to the different estimates of specific 

 limits entertained by different authors, it is not possible to com- 

 pare the Ceylon Mora accurately with that of any other tropical 

 island, except that of Jamaica, which, as we gather from Grisebach's 

 Flora of the British "West Indies, contains about 1092 species of 

 flowering plants. The latitudes, areas, and elevations of these islands 

 respectively are — 



Latitude. Area. Elevation. Gen. Sp. 



Jamaica 18° N. 4256 miles 8000 ft. 735 1840 



Ceylon 6— 10° N. 24,600 „ 8300 „ 933 2832 



This comparison would not be, however, a good one, for Jamaica 

 presents little variation of climate beyond what the elevation of the 

 Blue Mountains afford. In Ceylon, on the other hand, Mr. Thwaites 

 tells us that much of the variety of its vegetation is due to the great 

 difference of climate which the island presents. The southern part 

 possesses a humid very hot climate, equable temperature, and consi- 

 derable rainfall. The northern portion is hot and dry, being screened 

 by the hilly interior from the rainy south-west monsoon, and enjoys 

 but a short rainy season. The mountainous interior again presents 

 a considerable tract of cool very rainy districts. Hence, as Mr. 

 Thwaites remarks, the vegetation of the humid south is akin to that 

 of Sumatra and the Malay Archipelago. That of the dry northern 

 districts is identical wdth that of the Coromandel Coasts, and of the 

 hilly interior with the Neilgherrie Mountains. 



It is to be hoped that on some future occasion Mr. Thwaites will 

 enter fully into the subject of the relations of the vegetation to the 

 climate, and tell us how far he thinks the presence in Ceylon of 



