HISTORICAL NOTICES. IX 



American and European climates so characteristic of the 

 time. The climate of western Europe, in short, would, 

 under such a state of things, be greatly reduced in mean 

 temperature, the climate of America would suffer a less 

 reduction of its mean temperature, but would be much 

 less extreme than at present ; the general effect being the 

 establishment of a more equable but lower temperature 

 throughout the northern hemisphere. 



" The establishment of the present distribution of land 

 and water, giving to America its extreme climate, leaving 

 its seas cool and throwing on the coasts of Europe the 

 heated water of the tropics, would thus affect but slightly 

 the marine life of the American coast, but very materially 

 that of Europe, producing the result already referred to, 

 that our Canadian pleistocene fauna differs comparatively 

 little from that now existing in the gulf of St. Lawrence, 

 though in so far as any difference subsists it is in the 

 direction of an arctic character. The changes that have 

 occurred are perhaps all the less that so soon as the 

 Laurentide hills to the nortli of the St. Lawrence valley 

 emerged from the sea, the coasts to the south of these 

 hills would be effectually protected from the heavy 

 northern ice drifts and from the arctic currents, and 

 would have the benefit of the full action of the summer 



Pacific coast ; but, on the other hand, the occurrence of many species 

 common to the two sides implies a connection in comparatively recent 

 times, and similar evidence is afforded by the modern deposits of the 

 Isthmus. 



Upham reports from Dr. Maack, in the reports of explorations for 

 the Panama canal, the fact that on the watershed between the Atlantic 

 and Pacific a "vast area" of the Isthmus is occupied with "late 

 tertiary " beds holding shells of living species. This would confirm 

 the supposition based on the grounds that a passage across the Isthmus 

 existed in pleistocene times. — American Geologist, December, 1890. 



