358 ILLOGICAL GEOLOGY. 



tablisbmcnt of tlicir races. The clianccs of early coloniza 

 tion are immensely in favour of species which, multiplying by 

 agamogenesis, can people a whole shore from a single germ ; 

 and immensely against species which, multiplying only by 

 gamogcnesis, must be introduced in considerable numbers 

 .that some may survive, meet, and propagate. Thus we in 

 fer that the earliest traces of life left in the sedimentary de 

 posits near these new shores, will be traces of life as humble 

 :us that indicated in the must ancient rocks of Great IJrit- 

 ain and Ireland. Imagine now that the processes we have 

 briefly indicated, continue that the emerging lands become 

 wider in extent, and fringed by higher and more varied 

 shores; and that there still go on those ocean-currents 

 which, at long intervals, convey from far distant shores 

 immigrant forms of life. What will result? Lapse of 

 time will of course favour the introduction of such new 

 forms: admitting, as it must, of those combinations of lit 

 conditions, which, under the 1 law of probabilities, can occur 

 only at very distant intervals. Moreover, the increasing 

 area of the islands, individually and as a group, implies in 

 creasing length of coast ; from which there follows a longer 

 line of contact with the streams and waves that bring drift 

 ing masses ; and, therefore, a greater chance that germs of 

 fresh life will be stranded. 



And once more, the comparatively-varied shores, pre 

 senting physical conditions that change from mile to mile, 

 will furnish suitable habitats for more numerous spccieK. 

 So that as the elevation proceeds, three causes conspire to 

 introduce additional marine plants and animals. To what 

 classes will the increasing Fauna be for a long period coi,- 

 fined ? Of course, to classes of which individuals, or their 

 germs, are most liable to be carried far away from their native 

 chores by floating sea-weed or drift-wood ; to classes which 

 are also least likely to perish in transit, or from change of cli 

 mate ; and to those which can best subsist around coasts 



