of the Arctic nn<i the Anturrfir FdU/m.*. 307 



Other Vikws. 



'I'liis i;* |)crlia|)s the fittest place to discuss some of the 

 other views which liave a hearing on the question before us. 

 A few investigators have admitted tliat it is necessary to 

 assume a climate of tropical warmth in our latitudes to 

 explain the Early Tertiary fauna ; some of these, however, 

 regard it as a local phenomenon, while others call in the aid 

 of cosmic changes on a large scale. 



There is on the whole earth no other spot where all the 

 factors which make for the amelioration of the climate and 

 the wanning of the surface-water are combined in anything 

 like the same degree as on the W'^estern and North-western 

 coasts of Europe; it seems impossible to find conditions 

 better fitted to bring about this result than tliose now pre- 

 vailing; so that in general this objection is hardly entitled to 

 serious consideration. 



Other investigators incline to the view that the earth's 

 axis has so altered its position either within the earth itself 

 or in relation to the earth's orbit that tho climatic zones of 

 earlier geological times were quite differently arranged, and 

 ma)' have shifted periodically over the earth's surface. But 

 astronomers refuse to admit the possibility of variation on 

 such a scale, and geology and paleontology offer no evidence 

 of it. Moreover, from the paljeontological records of the 

 Tertiary period it can be proved that there is no groun 1 for 

 such an assumption, at least in regard to tliat period, with 

 wiiich we are alone concerned. 



We are now in a position to see that there is no argument 

 of any weight against regarding the Early Tertiary fauna as 

 one of tropical habit. VVe have further seen that a climato- 

 logical consideration of the problem excludes the theory that 

 the fauna was a local one. (ieological-paheontulogical inquiry 

 yields the same result, inasmuch as the Early Tertiary tauuas 

 of tropical habit have been demonstrated from the most 

 different parts of the earth, even from the southern hemi- 

 sphere. We have accordingly to assume that in those times 

 a climate of tropical warmth, with a fauna of tropical cha- 

 racter, extended over the greater portion of the temperato 

 zones. 



Origin of Zonally-disposed Faunas. 



Now that we have seen that the climatological considera- 

 tion of the Early Tertiary by reference to its launistic 

 materials is a scientifically justified standpoint, we have every 

 ground tor maintaining this standpoint with regard to the 



