MEAN ANNUAL TEMPERATURES. 141 



zerland (supposing it brought down to the sea-level, and the 

 Alps reduced to a low hill- country) a mean annual tempera- 

 ture of 12'13 Cent, (or 53'83 Fahr.) at the sea-level,, and of 

 ll-63 Cent, (or 52'93 Fahr.) at an elevation of 230-250 feet 

 above the sea. Consequently, assuming that the mean annual 

 temperature of the Swiss Lower Miocene was 20'5 Cent, (or 

 68-9 Fahr.), that of the Swiss Upper Miocene 18'5 Cent. 

 (or 65' 3 Fahr.), and the elevation above the sea 250 feet, the 

 temperature of the Lower Miocene will have been 8'87 Cent, 

 (or 15'96 Fahr.) higher, and the temperature of the Upper 

 Miocene 6'87 Cent, (or 12*36 Fahr.) higher than at present. 

 Thus in the Lower Miocene times the climate of Europe was 

 probably 9 Cent, (or 16'2 Fahr.) hotter than at present ; and 

 in the Upper Miocene period the climate had an elevation of 

 temperature of 7 Cent, (or 12'6 Fahr.) above the European 

 climate of the present day. 



Water exerts great influence upon the life arid development 

 of plants. The great abundance of woody plants and evergreen 

 trees, the numerous marsh-plants, and the lignite-deposits, indi- 

 cating extensive peat-mosses, leave no doubt that the climate was 

 humid, and the rainy days probably spread over the greater part 

 of the year. In this respect it will have differed considerably 

 from that now prevailing in the Canary Islands and Madeira, 

 and probably approached nearer to that of Louisiana and the 

 southern United States generally, in which extensive swamps 

 also occur suck as must have existed in the Miocene district. 



Among the animals of the Swiss Miocene the types of the 

 warm zones predominate ; but with them are mixed others which 

 belong to temperate and tropical climates. Not only do the 

 large and striking animals, such as the crocodiles, the great 

 tortoises and gigantic frogs, the tapirs and rhinoceroses, opos- 

 sums and apes, give to the Swiss Miocene fauna the character 

 of the warm subtropical zones, but similar proofs of a warm 

 climate are furnished by the wonderful multiplicity of forms in 

 the little population of insects which enlivened the primaeval 

 forest and the quiet lakes and streams of Miocene land. 



Marine animals were also influenced by conditions of tempe- 

 rature ; and species of the same animals still living depend upon 

 similar conditions of life to those which characterized them in 



