form with the climatic zones, though not always with the parallels 

 of the geographer." 



Mr. Allen contends * that 



" In fact, so generally is temperature recognized by the leading 

 writers on the distribution of marine life that it seems superfluous 

 to reiterate or emphasize this principle. That the zones of life 

 should be perhaps a little less obvious over the land areas in con 

 sequence of the diversity of contour resulting from differences of 

 elevation, and the interruptions and exceptional conditions due to 

 mountain chains and high plateaus than over the oceanic expanses, 

 is naturally to be expected. That there is, however, a similar cor 

 respondence between climatic belts and the zones of life seems to me 

 abundantly evident. As has been already shown, the broader or 

 primary zones are, first, an Arctic or North Circumpolar Zone, em 

 bracing the arctic, subarctic, and colder temperate latitudes of the 

 northern hemisphere, throughout the whole of which area there is 

 a marked homogeneity of mammalian life, as well as of animal and 

 vegetable life in general ; secondly, that below this there is a broad 

 belt of life, which, in its general fades, is distinctive of the tem 

 perate and warm-temperate latitudes, and that these two zones of 

 life are far more closely related inter se than with the life of the in- 

 tertropical regions, with which regions they may be collectively con 

 trasted, and together receive the appropriate name of ' Arctogcea ; ' 

 thirdly, it has been shown, so far as the northern hemisphere is 

 concerned, that the life of the tropical and temperate regions of the 

 same continent is more widely different than is the life of corre 

 sponding portions of the temperate and colder parts of the (so-called) 

 Old World and the New; fourthly, that the life of Tropical 

 America has very little in common with that of the tropical por 

 tions of Asia and Africa ; fifthly, that the life of the South Tem 

 perate Zone presents a fades distinct from that of the tropics, and 

 has still less in common with that of the North Temperate Zone ; 

 sixthly, that Australasia is so highly differentiated as to form a dis 

 tinct primary region, having little in common with other lands, 

 even with those of contiguous regions, or those having a similar 

 geographical position ; seventhly, that Madagascar and its contig 

 uous islands, while to some extent African in affinity, form also a 

 highly specialized region ; lastly, that the antarctic and cold south- 



* Allen, op. cit., pp. 373-375- 

 I 



