OF CREATION. 185 



habitation and burial-place of many successive races of 

 beings ; but there is nowhere evidence of such con- 

 siderable or violent change as would justify us in sepa- 

 rating the series into two or more parts. The whole 

 was probably continuous ; and, although aifected by 

 contemporaneous and successive disturbances fre- 

 quently repeated, these hardly involved any changes 

 of great moment modifying the general result. 



The inhabitants of the sea during the oolitic 

 period include, as might be expected, a vast mul- 

 titude of species. Of these some were attached per- 

 manently to marine bodies, and so were partly or 

 entirely dependant on a particular mechanical, chemi- 

 cal, or mineralogical condition of the sea bottom ; 

 others were attached less permanently, possessing 

 only imperfect powers of locomotion, and limited as 

 to the depth at which they conveniently live ; while 

 there were others, again, swimming freely in the 

 ocean, and limited only in their range by the nature 

 of the supply of food. The first-mentioned of these 

 groups includes the coral animal and many others of 

 low organization, the next comprehends the encrinites, 

 star-fishes, sea-urchins, &c., as well as a number of 

 crustaceans and insects, and a large proportion of the 

 animals enclosed in shells ; while the last, in some 

 respects the most important and interesting group, 

 includes the more highly organized mollusca, the 

 fishes, and the marine reptiles. It will be convenient 

 to describe, first, these different groups of the inha- 

 bitants of the ocean, and then proceed to the account 

 of the land animals of the period. 



The corals of the oolitic seas formed some con- 

 siderable reefs and islands, especially during the mid- 



