92 



MIOCENE FAUNA. 



are still living, or 35 per cent. ; of the 360 species of the sub- 

 alpine Molasse, 125 (or a similar proportion, 35 per cent.}. The 

 Shell-sandstone and the subalpine Molasse together possess 421 

 species, of which 147 (or the same proportion of 35 per cent.) 

 occur in the existing fauna. The two faunas consequently possess 

 precisely the same relation to the existing fauna, not only in 

 the numerical proportions, but also in the manner in which the 

 living species are now distributed ; only the fact must be taken 

 into consideration, that Prof. Heer knows 152 species more from 

 the subalpine Molasse than from the Shell-sandstone. A resume 

 of numbers is given in the following Table : 



This summary shows that most of the species now living, both 

 from the Shell-sandstone and the subalpine Molasse, belong to 

 the Mediterranean * ; but that a number of tropical forms are 

 mixed with them, among which African types are more nume- 

 rous than Asiatic. Thus the two faunas stand in the same 

 relation to the existing fauna, and they must consequently be 

 ranged in the same stage. The differences between them are 

 caused less by time than by local circumstances. The Shell- 



* Almost all the species in the first column also live in the Mediterranean. 

 About one third of the species are now exclusively confined to the Mediter- 

 ranean. Nine species of the second column occur also in tropical Africa ; so 

 that the Swiss Molassic fauna altogether possesses twenty-one tropical 

 African forms, nine of which, however, still inhabit the southern coast of 

 Europe. 



