Ch. XV.] 



UPPER MIOCENE STRATA, SWITZERLAND. 



251 



extreme slowness. Although the fossiliferous beds are, in the aggre- 

 gate, not more than a few yards in thickness, and have only been 

 examined in the small area comprised in the two quarries just alluded 

 to, they give us an insight into the state of animal and vegetable life 

 in part of the Upper Miocene period, such as no other region in the 

 world has elsewhere supplied. In the year 1859, Professor Heer had 

 already determined no less than 475 species of plants and 900 insects 

 from these QEningen beds. He supposes that a river entering a lake 

 floated into it some of the leaves and land-insects, together with the 

 carcasses of quadrupeds, such as the great Mastodon. Occasionally, 

 during tempests, twigs and even boughs of trees with their leaves 

 were torn off and carried for some distance so as to reach the lake. 

 Springs, containing carbonate of lime, seem at some points to have 

 supplied calcareous matter in solution, giving origin locally to a kind 

 of travertin, in which organic bodies sinking to the bottom became 

 hermetically sealed up. The laminae, says Heer, which immediately 

 succeed each other, were not all formed at the same season, for it can 

 be shown that, when some of them originated, certain plants were in 

 flower, whereas, when the next of these layers was produced, the 

 same plants had ripened their fruit. This inference is confirmed by 

 independent proofs derived from insects. The principal insect-bed is 

 rarely two inches thick, and is composed, says Heer, of about 250 

 leaflike laminae, some of which were deposited in the spring, when 

 the Cinnamomum polymorphum (p. 254) was in flower ; others in 

 summer, when winged ants were numerous, and when the poplar and 

 willow had matured their seed ; others, again, in autumn, when the 



Fig. 180. 



Fig. 181. 



\SU 



Podogonium Knorii. Upper Miocene of (Eningen and many parts of Germany. 



Fig. ISO. Restoration of the plant by Prof. Heer. Frontispiece, Flora Tert. Hel. \ nat. size. 



a. Branch bearing flowers before the leaves appear. o. Branch with leaves and ripe fruit. 



Fig. 181. a. Pod of P. Knorii. (Eningen. \ nat. size. e. Formica lignitum. 



o. Leaf of gramineous plant. d. Hister coprolitlwrum. 



Heer, pi. 134, fig. 26. 



was in fruit, as well as 



same Cinnamomum polymorphum (fig. 1 



the liquidambar, oak, clematis, and many other plants 



The ancient lake seems to have had round its borders a belt of 



