120 Dr. R. P. Cotton's Observations on the 



Tims of forty-two distinct Mammalia, twenty are found in 

 both positions, seventeen are limited to the caverns, and five 

 are found exclusively in freshwater strata. 



From a mere survey of such a table, conclusions as to the 

 relative age of the two series would be inaccurate; and it be- 

 comes necessary to consider the various circumstances under 

 which each may have arisen, and the influence which the 

 habitats of the various animals may have exercised upon the 

 position of their remains. 



The valley of the Thames, in many places so abundant in 

 animal remains that a metiopolitan churchyard could hardly 

 boast of a greater collection of bones, presents some peculiari- 

 ties worthy of attention, and bearing closely upon the point. 

 The bones are in general in a good state of preservation, and 

 often make up nearly the entire skeleton ; but occasionally 

 some fragments are met with, not resulting from original vio- 

 lence when deposited (as they are often surrounded by the 

 most delicate freshwater shells) or careless removal, but appa- 

 rently broken before carried to their place of interment. I'he 

 frequency of animal remains appears to be just in proportion 

 to their size, the small bones of large mammalia being much 

 more uncommon than the larger ones, and the young of such 

 animals as the Mammoth, Rhinoceros, and Hippopotamus 

 being rarely met with, whilst all indications of the smaller 

 genera so common in caverns are altogether absent. I have 

 collected from these Pleistocene beds, chiefly at Ilford, remains 

 ofthe following animals: — Mammoth, Rhinoceros, Ox, Auroch, 

 Horse, Irish Elk, Deer, Bear, Sheep, Pig and Bird ; but the 

 first four only can be called abundant, and of these the Mam- 

 moth and Rhinoceros are at least ten times more frequent than 

 the other two — the rest are but seldom met with. The Bear 

 is the only representative of Carnivora, and of it only one 

 specimen has been found ; and the only evidence of a Bird 

 consists of an ulna, of which more will be said hereafter. 



U|)on looking at such a collection, it is impossible to sup- 

 pose that it can lepresent the whole creation of any geological 

 period, or that such a mass of Mammalia can have been with- 

 out an ample number of destroyers; for although the Tiger 

 and Hyaena have been found in deposits of the same age, they 

 are rare, and bear a very insignificant proportion to the Her- 

 bivora. 



The bone-caverns reveal a set of circumstances exactly the 

 opposite ofthe above. In these, several genera of Carnivora 

 are abundantly preserved; and the bones with which they are 

 associated belong either to a class of smaller animals or the 

 young of the larger ones, and a collection of these remains 

 equally fail in presenting us with representatives of an entire 



