146 MIOCENE CLIMATE. 



those in tropical seas ; and the eastern sea which washed Styria 

 in Lower Miocene times likewise presents extensive reef-forma- 

 tions, which may be traced up to 47 and 48 N. lat. The 

 Swiss sea was destitute of these coral-formations, as was also the 

 ocean which in the Lower Miocene period spread over Germany. 

 With regard to the marine fauna that lived in the Helvetian pe- 

 riod on the shores of Madeira and Porto Santo, Prof. Heer has 

 had interesting information from M. Carl Mayer *. Although 

 this fauna approaches the organic remains of the Middle Miocene 

 of Europe, it contains more tropical forms ; and in Porto Santo 

 large stony corals occur. At present the islands of the Madeiran 

 and Canarian groups are quite destitute of coral reefs, and the 

 marine fauna has a less southern character than that of which 

 the remains are imbedded in the Miocene tuff's. Out of the 

 169 species of Mollusca that Mayer has determined, 65 are still 

 living, or 38 per cent. The majority of these species live in the 

 Lusitanian and Mediterranean zones; but 19 of the species are 

 now found only between the tropics. The tropical forms there- 

 fore in this case constitute 29 per cent, [of the living species], 

 whilst among the Mollusca of the Helvetian stage in Switzerland 

 the proportion is only 14 per cent., which shows that at that 

 time the waters of those regions had a higher temperature than 

 either those of the Swiss Miocene sea or those of the present 

 seas in the same latitudes. 



There is a formation in Java which, according to recent in- 

 vestigations, is to be regarded as Upper Miocene, but which may 

 perhaps be younger ; and the fossil plants in these strata approach 

 nearly to those of the existing flora of Java; also the majority 

 of the fossil marine animals found therein still possess their 

 descendants in the Indian seas, or have their nearest relatives 

 in those waters. Hence these plants and animals lived under 

 similar climatic conditions, in the Miocene period, to those now 

 prevalent; and if this formation really belongs to the Upper 

 Miocene, it would follow that the -temperature in the tropics 

 was then the same as in our times. 



* See M. 0. Mayer's " Systematisches Verzeichniss der fossilen Reste von 

 Madeira, Porto Santo, und Santa Maria," in Dr. G. Hartung'8 ' Geologische 

 Beschreibung der Insel Madeira und Porto Santo/ Leipzig, 1864. 



