LAKE OF (EX1XGEX. 



isolated leaves of land-plants. But the upper bed contains large 

 pikes, and has furnished gigantic frogs, a small tortoise, a fine 

 large salamander, and the bones of calling-hares. In the bed 

 called the " Dillstecken" the plants have entirely disappeared. 

 Probably the shore part of the lake gradually became shallower, 

 the mouth of the river no longer maintained its position, and by 

 degrees the marshy ground was laid dry. Hence the bed of 

 calcareous marl hardened, and a number of regular fissures were 

 formed in it, dividing its entire surface into quadrangular clods. 

 In this manner the origin of the singular sharp-edged blocks 

 formed by the deposit may be explained. Volcanic action may 

 have assisted in the drying-up of the stratum ; and afterwards 

 the district was again laid under water, probably on account ot 

 the mouth of the river having been brought into its vicinity. 

 First of all a number of pond-mussels (Anodonta Lavattri} esta- 

 blished themselves in the locality; their shells now cover the 

 rock which overlies the " Dillstecken/' and is coarse and sandy, 

 showing that at the time of its formation the bottom of the lake 

 was covered with sand. The ground was well fitted to receive 

 the sand-loving Isoctcs Braunii, which has been found there in 

 great abundance and formed a dense green tuft ; it also produced 

 a pondweed (Potamogeton geniculatus) , which appears in such 

 quantities that the stone is permeated by it in all directions, and 

 has received from it a dark colour. On the shore, reeds, willows, 

 and poplars again appear. The number of species of plants, 

 however, is small, and there are but few in the strata next 

 dbove it, which have recaived the names of " cotton-bed/'' " black 

 bed," " tortoise-bed," and "salamander-bed/' the last two being 

 the chief sources of large tortoises and salamanders. It would 

 appear that the bottom of the lake had become deeper, or that 

 it was removed further from the shore, so that the leaves which 

 were floated into the lake no longer reached this point. The 

 black bed alone contains many leaves, but almost exclusively 

 those of a poplar and a willow (Populus mutabilis and Salix an- 

 gusto) , which shows that these two species must have grown in 

 abundance upon the shore. 



The sahimander-bcd is overlaid by about 4 feet of a hard 

 limestone, known as the great and little " Mockeii." The great 



