SKCT. XXVH. DISTRIBUTION OF ANIMALS. 269 



science, the phenomena observed have led to the con- 

 clusion that vegetable creation must have taken place in 

 a number of distinctly different centers, each of which 

 was the original seat of a certain number of peculiar 

 species, which at first grew there and nowhere else. 

 Heaths are exclusively confined to the Old World, and 

 no indigenous rose-tree has ever been discovered in the 

 New; the whole southern hemisphere being destitute 

 of that beautiful and fragrant plant. But this is still 

 more confirmed by multitudes of particular plants hav- 

 ing an entirely local and insulated existence, growing 

 spontaneously in some particular spot and in no other 

 place ; for example, the cedar of Lebanon, which grows 

 indigenously on that mountain, and in no other part of 

 the world. On the other hand, as there can be no doubt 

 but that many races of plants have been extinguished, 

 Sir John Herschel thinks it possible that these solitary 

 instances may be the last surviving remnants of the 

 same groups universally disseminated, but in course of 

 extinction ; or that perhaps two processes may be going 

 on at the same time ; " some groups may be spreading 

 from their foci, others retreating to their last strong- 

 holds." 



The same laws obtain in the distribution of the ani- 

 mal creation. The zoophyte (N. 215), occupying the 

 lowest place in animated nature, is widely scattered 

 through the seas of the torrid zone, each species being 

 confined to the district best fitted to its existence. 

 Shell-fish decrease in size and beauty with their dis- 

 tance from the equator ; and as far as is known, each 

 sea has its own kind, and every basin of thelpean is in- 

 habited by its peculiar tribe of fish. Indeed MM. Peron 

 and Le Sueur assert, that among the many thousands 

 of marine animals which they had examined, there is 

 not a single animal of the southern regions which is not 

 distinguishable by essential characters from the analo- 

 gous species in the northern seas. Reptiles are not 

 exempt from the general law. The saurian (N. 216) 

 tribes of the four quarters of the globe differ in species ; 

 and although warm countries abound in venomous 

 snakes, they are specifically different, and decrease both 

 in numbers and in the virulence of their poison with de- 



