170 



In the foregoing table I have shewn the distribution of the 

 genera that are special to the Tertiary epoch, and in the 

 following I have arranged those which have representatives in 

 our present seas. The Hving species, however, are quite distinct 

 from the fossil forms. This table shews, as far as Zoophytes are 

 concerned, how gradually changes have taken place in organic 

 nature, by the dying out of one group of forms and the 

 introduction of others; and it at the same time illustrates the 

 general principle which is found to govern all other classes of 

 the animal kingdom, that every organism has a limited life in 

 time, and a limited range in space. 



A TABLE OF TEETIAEY GENEEA THAT OCCUE IN 

 MOEE THAN ONE PEEIOD. 



