198 



Considered in the most general point of view, without any re- 

 gard to the lacustrine beds which are perhaps local or acciden- 

 tal, the tertiary groups of the Paris basin may be described as a 

 great complex system of deposits belonging to one protracted zoo- 

 logical period ; characterized by extinct genera of mammalia, and 

 by innumerable marine shells; but affording very few species by 

 which we can connect them either with the chalk, or with the for- 

 mations of our neighbouring seas. Their position is therefore en- 

 tirely insulated ; and by what new links they may be connected with 

 the physical events which went before them and followed after them, 

 can only be determined by a long series of observations. I have 

 already pointed out the source from which some of the older links 

 may hereafter probably be supplied. Of the same palseotherian 

 age, and in the same insulated position, are the tertiary deposits of 

 Hampshire, and some of the great lignite formations in the north 

 of Germany. 



The next group of the tertiary system is ill defined, and still but 

 imperfectly understood. Some members of it are seen on the banks 

 of the Loire, and have formed the subject of a late important me- 

 moir by M. Desnoyers; and the same portion of the series is repre- 

 sented on the eastern coasts of England, by the beds of Crag over- 

 lying the London clay. It contains, like the former division, the 

 bones of many mammalia, some of extinct, and some probably of 

 living species ; but the remains of the extinct animals do not be- 

 long to the palaeotheria of the older period, but to the mammoth, 

 the rhinoceros, and other animals, of which the bones are found so 

 constantly in the superficial gravel. To the fossil shells of this di- 

 vision the same observations may be applied : many belong to spe- 

 cies which are unknown, and perhaps extinct ; others cannot be dis- 

 tinguished from the living shells of the neighbouring seas. 



A third division of the system may comprehend all the higher 

 Sub-Apennine deposits ; distinguished by the bones of mammalia in 

 still greater abundance, and by the number and beauty of the fossil 

 shells, many of which are of living species. It is of enormous 

 thickness in some of the low regions at the base of the Apennines ; 

 and it probably extends over a considerable portion of the basin of 

 the Danube, and over the plains beyond the eastern termination of 

 the Alps. I have, however, no time, nor do I possess information, 

 to give any detailed account of its distribution. 



During the periods in which the two last tertiary groups were 

 elaborated in the sea, there must have been deposited on the land, 

 in caverns, in fissures, and in beds of superficial gravel, many bones 

 of the same species of animals by which those groups are charac- 

 terized : and during the same periods may have originated in inland 

 lakes some of the deposits of which we now only see the traces 

 in masses of lacustrine marl found in various countries resting 

 unconformably upon the older strata. 



It is impossible with our present knowledge, to form even a con- 

 jecture respecting the subdivisions into which the whole tertiary 

 series may finally be separated. I am only anxious, in the mere out- 



