THE EUKOPEAN SEAS. 



7 



intersection of arms or promontories of land, and 

 the more powerful interruptions caused by the great 

 gulfs and abysses of the deep, or by vast and com- 

 paratively desert tracts of unprolific sand, which in 

 many places are spread out in extensive shallows, 

 are all powerful influences affecting the diffusion of 

 marine creatures, and determining their distribution 

 within certain and more or less defined limits. 



A province, as understood in the following chap- 

 ters, is an area within which there is evidence of 

 the special manifestations of the Creative Power ; 

 that is to say, within which there have been called 

 into being, the originals, or protoplasts, of animals or 

 plants. These may become mixed up with emi- 

 grants from other provinces, even exceeding in their 

 numbers the aborigines, so to call them, of the 

 region to which they have migrated. The distin- 

 guishing of the aboriginal from the invading popu- 

 lation, and the determination of the causes which 

 have produced and directed the invasion, are among 

 the problems which the investigator of the distri- 

 bution of animated creatures, has to endeavour to 

 solve. When the Fauna or Flora of a province has 

 been thoroughly investigated, the diffusion of the 

 individuals of the characteristic species is found 

 to indicate that the manifestation of the creative 

 energy has not been equal in all parts of the area, 

 but that in some portion of it, and that usually 

 more or less central, the genesis of new beings has 

 been more intensely exerted than elsewhere. Hence, 



