Vice-President's Address. ISl 



results that are due to latitude. It cannot have been 

 otherwise in former times. In all aL;es the tropics must 

 have received more direct sun heat than temperate and 

 Polar regions : and however much the climatic conditions of 

 the Palaeozoic era may have differed from the present — 

 however uniformly temperature may liave been distributed — 

 still, as I have said, absolute uniformity was impossible. It 

 was doubtless owing to the fact that the dry lands of 

 Palceozoic times were not only much less extensive than 

 now, but more interrupted, straggling, and insular, that the 

 climate of the globe was so equable. Under such geo- 

 graphical conditions, great oceanic currents would have a 

 much freer course than is now possible, and warm water 

 would find its way readily across wdde regions of the sub- 

 merged continental plateau into the highest latitudes. The 

 winds blowing athwart the land would everywhere be moist 

 and warm, and no such marked differences of temperature, 

 such as now obtain, would distinguish the Arctic seas from 

 those of much lower latitudes. At the same time, the 

 comparatively shallow water overlying the submerged areas 

 of the continental plateau would favour the distribution of 

 species, and thus bring about that wide distribution of 

 cosmopolitan forms and general similarity of fades, which 

 are such marked features of the Palaeozoic faunas. It is 

 even quite possible that migration may have taken place 

 here and there across the great oceanic depression itself; for 

 it may well be doubted whether, at so early a period, that 

 depression had sunk down to its present depth below the 

 level of the continental plateau. 



Yet, notwithstanding such facilities for migration, and the 

 consequent similarity of fades I have referred to, the 

 Palccozoic faunas of different regions have usually certain 

 distinctive characters. Even at the very dawn of the era 

 the marine faunas were already grouped into provinces, 

 sometimes widely separated from one another, at other 

 times closely adjacent, so that it is evident that barriers 

 to migration here and there existed. It could hardly have 

 been otherwise ; for local and more wddely-spread movements 

 of elevation and depression took place again and again 

 during Palaeozoic times. 



