54 GEOLOGICAL MEMOIRS. 



On the whole the number of land-conchyhse was formerly greater 

 and that of marsh-conchyliae smaller than at present, when we do 

 not include the brackish-water conchylise (Dreissena, Littorinella, 

 some Neritinae, Potamides). This same miocene basin has also fur- 

 nished to Kaup 17 genera and 32 species of land mammalia generally 

 large, to which H. v. Meyer has added a considerable number of spe- 

 cies mostly smaller. No spot on the surface of the earth of equal ex- 

 tent would now, it is probable, yield so many. 



V. The peculiar, freshwater, molasse-marls of Oningen, in like 

 manner belonging merely to a small unbroken time of deposition, have 

 as yet furnished : 



Genera. Species. 



Plants according to Al. Braun* 32 55 



Non-marine molluscs oo oo 



Insects according to O. Heer, first Coleoptera 70 103 



others oo oo 



Freshwater fishes according to Agassiz .... 13 19 



Reptiles according to H. v. Meyer (especially 



I5atrachians) 12 16 



Birds * -5f 



JMammalia according to 11. v. Meyer 3 4 



130-l-x; 197+x. 



All these remains, except those of the non-marine molluscs, fishes 

 and some reptiles, have only come accidentally into this situation, 

 and hence can in no way represent the entire fauna of that time. 

 Tlie Batrachians there appear more numerous and varied among the 

 reptiles than in any other locality in Europe, perhaps on the whole 

 face of the earth. Then of living freshwater fishes there were known 

 by 



Genera. Species. 

 Hartmann in all Switzerland .... 13 44 



,, in the Boden-lake .... — 30 "1 The above is 



Nau near Mayence 10 33 > thus j- of this 



V. Martens near Ulm 10(13) 35 J amount ; 



but it would be impossible to find these j- of the species in any of 

 the places mentioned collected in a single (small) basin of water. 

 Parschlug is of the same age with Oningen, and has produced 

 some identical insects, mammalia, and, according to linger, also 

 67 genera with 140 species of plants, of which 19 hkewise occur 

 at Oningen. They are leaves, almost wholly of trees and shrubs, 

 which could not be found assembled in such variety in any existing 

 forest, so that linger has been compelled to make the supposition 

 that they have been brought together by floods from a wide circuit, 

 although their state of preservation appears opposed to this view. 



These examples may suftice to render it highly probable, even 

 although all classes, orders, and families of our system may not have 

 existed at all times on the surface of the earth, and although some 



* Jahrbuch, 1845, p. 164. 



