374 ALTERNATE GLACIAL PERIODS 



growing on the summits of the mountains of Borneo. Some 

 of these Australian forms, as I hear from Dr. Hooker, extend 

 along the heights of the peninsula of Malacca, and are thinly 

 scattered on the one hand over India, and on the other hand 

 as far north as Japan. 



On the southern mountains of Australia, Dr. F. Miiller has 

 discovered several European species; other species, not in- 

 troduced by man, occur on the lowlands ; and a. long list can 

 be given, as I am informed by Dr. Hooker, of European gen- 

 era, found in Australia, but not in the intermediate torrid 

 regions. In the admirable " Introduction to the Flora of 

 New Zealand," by Dr. Hooker, analogous and striking facts 

 are given in regard to the plants of that large island. Hence, 

 we see that certain plants growing on the more lofty moun- 

 tains of the tropics in all parts of the world, and on the tem- 

 perate plains of the north and south, are either the same 

 species or varieties of the same species. It should, however, 

 be observed that these plants are not strictly arctic forms ; 

 for, as Mr. H. C. Watson has remarked, "in receding from 

 polar toward equatorial latitudes, the alpine or mountain 

 flora really become less and less arctic." Besides these 

 identical and closely allied forms, many species inhabiting 

 the same widely sundered areas, belong to genera not now 

 found in the intermediate tropical lowlands. 



These brief remarks apply to plants alone ; but some few 

 analogous facts could be given in regard to terrestrial ani- 

 mals. In marine productions, similar cases likewise occur ; 

 as an example, I may quote a statement by the highest 

 authority, Professor Dana, that " it is certainly a wonderful 

 fact that New Zealand should have a closer resemblance in 

 its Crustacea to Great Britain, its antipode, than to any other 

 part of the world." Sir J. Richardson, also, speaks of the 

 reappearance on the shores of New Zealand, Tasmania, etc., 

 of northern forms of fish. Dr. Hooker informs me that 

 twenty-five species of algae are common to New Zealand 

 and to Europe, but have not been found in the intermediate 

 tropical seas. 



From the foregoing facts, namely, the presence of temper- 

 ate forms on the highlands across the whole of equatorial 

 Africa, and along the peninsula of India, to Ceylon and the 

 Malay Archipelago, and in a less well-marked manner across 

 the wide expanse of tropical South America, it appears almost 

 certain that at some former period, no doubt during the most 

 severe part of a Glacial period, the lowlands of these greafc 



