PREFACE. VII 



The knowledge of the distribution of animals 

 may be of importance in another point of view, 

 as affording collateral assistance to the Geolo- 

 gist in determining the character of the muta- 

 tions of the earth. For as at the present time 

 similar climates, however distant, however much 

 isolated from each other, are peopled by similar 

 creatures, so probably it has ever been ; and 

 this would seem to point to a period or periods 

 when they were universally diffused : a diffu- 

 sion which subsequent geological changes have 

 very remarkably deranged. If all animated crea- 

 tion ever existed at any one epoch, the climate 

 and condition of the earth's surface must have 

 been so peculiar, that we can form no idea of 

 them at the present time. While the geologists 

 thus look to Natural History for assistance in 

 solving some of their obscure problems, the 

 Naturalists must in turn look to Geology for 

 assistance in deciphering the system which 

 nature has followed in forming her productions. 

 In the existing races of beings there are many 

 wide chasms which divide creation into irre- 

 gular masses, which have hitherto defied all 

 attempts at successful classification. But geo- 

 logists are daily discovering extinct forms, which 

 are filling up the vacancies, and which even- 

 tually may unite creation into an harmonious 

 whole. 



The Zoophytes at present existing on our 

 shores are small and fragile when compared 



