183 



CHAP. XL 



CLASSIFICATION. 



Number and Variety of Organic Forms. Generalisation. 

 Classification of the Animal Kingdom. 



IMPERFECTLY as we are able to investigate the 

 zoology of the ocean, and although by far the 

 greater part of the vast expanse beneath the sur- 

 face of which the various objects of our research 

 have their abode is unknown and unexplored, 

 there is abundant reason to believe that the sub- 

 aqueous realms are much richer in the number 

 and variety of the organic forms that inhabit them, 

 than the terrestrial portions of the globe. 



Speaking of the myriads of living creatures 

 whose existence is connected with one species of 

 sea-weed found in the southern ocean, Darwin 

 makes the following remarks : " The number of 

 living creatures of all orders whose existence 

 depends on that of the kelp is wonderful. A 

 great volume might be written describing the 

 inhabitants of one of those beds of sea-weed. 

 Almost every leaf, excepting those that float on 

 the surface, is so thickly encrusted with coral- 

 lines as to be of a white colour. We find ex- 

 quisitely delicate structures, some inhabited by 

 simple hydro-like polypi ; others by more or- 



M 4 



