GEOLOGICAL SOCIKTY OF LONDON. 177 



liarity would almost give rise to a suspicion of not merely a 

 different variety of the tetracaulodon, but even of a new 

 genus.'^ The tetracaulodon tapiroides has received its specific 

 name from the resemblance of its first grinder to the molar 

 of the tapir. An upper jaw in Mr. Koch^s collection con- 

 tains two tusks, bent downwards like those of the morse, and 

 thickly covered with enamel ; and they plainly indicate, he 

 says, that the animal fed on water-plants. In conclusion, the 

 author calls attention to some peculiar vertebree which were 

 found associated with the skull and lower jaws of the tetracau- 

 lodon, and he is of opinion that they exhibit characters in 

 accordance with the supposed aquatic habits of that animal. 



On the Flat Regions of Central and Southern Russia, in Eu- 

 rope. By Mr, Murchison, M. de Verneiiil, and Count 

 Keyserling, 



This paper, which occupied the greater part of the first, 

 and the whole of the second evening, included in our notice, 

 described the flat regions of Russia traversed by the authors 

 during the summer of 1841 ; the second, devoted by them 

 to the examination of that empire ; and the account of Ural, 

 or mountainous districts, is reserved for subsequent meet- 

 ings. The formations which occupy this vast territory belong 

 to the Silurian, Devonian, and carboniferous systems; to a 

 great series of deposits equivalent in geological position with 

 the magnesian limestone of England and the zeclistein of 

 Germany, and to certain portions of the oolitic, cretaceous, 

 and tertiary systems, the whole being overlaid by far-spread- 

 ing masses of northern drift and other detritus. It is impos- 

 sible, in a notice suited to our Journal, to grapple with the 

 details of a paper, describing, for the first time, the true 

 order of position of strata extending over twelve degrees of 

 latitude and thirty degrees of longitude ; but we will endea- 

 vour to give an analysis of the conclusions arrived at by the 



VOL. I. NO. VI. N 



