CONCLUSIONS. 383 



has not been seen since 1768. According to all appearances, 

 we must also reckon among these the great stag, the skeleton 

 and horns of which have been found buried in the peat-bogs 

 of Ireland, and those of the Isle of Man. There are also 

 many species of animals whose numbers are daily diminishing, 

 and whose extinction may be foreseen ; as the Canadian deer 

 ( Wapiti), the ibex of the Alps, the L'dmmeryeyer, the bison, 

 the beaver,, the wild-turkey, &c. 



. 630. Other causes may also contribute towards dispersing 

 animals beyond their natural limits. Thus the sea-weeds are 

 carried about by marine currents, and are frequently met with 

 far from shore, thronged with little crustaceans, which are in 

 this manner transported to great distances from the place of 

 their birth. The drift-wood which the Gulf stream floats 

 from the Gulf of Mexico even to the western shores of Europe, 

 is frequently perforated by the larvae of insects, and may 

 probably serve as depositories for the eggs of fishes, Crustacea 

 and moliusks. It is possible also that aquatic birds may con- 

 tribute in some measure to the diffusion of some species of 

 fishes and moliusks, either by the eggs becoming attached to 

 their feet, or by means of those which they evacuate undi- 

 gested, after having transported them to considerable dis- 

 tances. Still, .all these circumstances exercise but a very 

 feeble influence upon the distribution of species in general, and 

 each country, none the less, preserves its peculiar physiog- 

 nomy, so far as its animals are concerned. 



631. There is only one way to account for the distribu- 

 tion of animals as we find them, namely, to suppose that they 

 are autochthonoi, that is to say, that they originated like 

 plants, on the soil where they are found. In order to explain 

 the particular distribution of many animals, we are even led 

 to admit that they must have been created at several points of 

 the same zone, an inference which we must make from the distri- 

 bution of aquatic animals, especially that of fishes. If we ex- 

 amine the fishes of the different rivers of the United States, pe- 

 culiar species will be found in each basin, associated with others 

 which are common to several basins. Thus, the Delaware 

 River contains species not found in the Hudson ; but, on the 

 other hand, the pickerel is found in both. Now, if all animals 

 originated at one point, and from a single stock, the pickerel 

 must have passed from the Delaware to the Hudson, or vice 



