16 



of the globe, the pabulum of volcanic fires, the source of 

 earthquakes, and the most powerful agent in the changes 

 continually going on in the interior and on the surface of 

 the earth. It gives off the materials of clouds, rain, snow, 

 and hail, which give origin to springs, rivers, lakes, gla- 

 ciers, icebergs, and many grand and interesting appear- 

 ances of nature* Water is the nourishment of the Vege- 

 table Kingdom, and is necessary to the support of most 

 animals. A knowledge of that branch of Natural History 

 which treats of the waters of the globe, is important to the 

 Zoologist, as explaining the physical and geographical dis- 

 tribution, and the habits of aquatic animals. It accounts 

 for the showers of animals that frequently fall from the 

 atmosphere, as of fishes, frogs, shells, worms, &c. The 

 ova of Zoophytes are not, like those of fishes, fixed by the 

 parent in a situation favourable for their development, 

 but are committed, like the seeds of marine plants, to the 

 mercy of the waves, so that their distribution is regulated 

 chiefly by the currents and motions of the sea, which Hy- 

 drography points out. The immense body of heated waters 

 borne by the gulf stream through the Atlantic from the 

 Equator towards the Arctic seas, conveys with it into high 

 latitudes the temperature of tropical seas a circumstance 

 which enables us to account for the occurrence of ani- 

 mals along its course in latitudes far beyond their natural 

 climate. 



The study of the Animal Kingdom is inseparably con- 

 nected with the science of Geology. No useful information 

 respecting fossil animals can be learned or communicated 

 without some acquaintance with the strata in which they 

 occur, and with the general structure of the crust of the 

 earth. And the successful study of extraneous fossils re- 

 quires a very extensive acquaintance with the structure 

 and character of the existing races, the nature and history 

 of extinct animals being determined chiefly by a compa- 

 rison with allied existing species. It is by finding accumu- 

 lations of organic remains, spread over successive strata deep 



