COLONIZATION OF THE NEW CONTINENT. 359 



comparatively bare of life. Evidently, then, corals, annelids, 

 inferior molluscs, and crustaceans of low grade, will chiefly 

 constitute the early Fauna. The large predatory members 

 of these classes, will be later in establishing themselves ; 

 both because the new shores must first become well jdco- 

 pled by the creatures they prey on, and because, being 

 more complex, they or their ova must be less likely to 

 Biirv:ve the journey, and the change of conditions. 



We may infer, then, that the strata deposited next after 

 the almost " azoic " strata, would contain the remains of 

 invertebrata, allied to those found near the shores of Australia 

 and South America. Of such invertebrate remains, the low- 

 er beds would furnish comparatively few genera, and those 

 of relatively low types ; while in the upper beds the num- 

 ber of genera would be greater, and the types higher : just as 

 among the fossils of our Silu rian system. As this great geolo- 

 gic change slowly progressed through its long history of 

 earthquakes, volcanic disturbances, minor upheavals and sub- 

 sidences — as the extent of the archipelago became greater 

 and its smaller islands coalesced into larger ones, while its coast 

 line grew still longer and more varied, and the neighbouring 

 sea more thickly inhabited by inferior forms of life ; the lowest 

 division of the vertebrata would begin to be represented. 

 In order of time, fish would naturally come after the lower 

 invertebrata : both as being less likely to have their ova 

 transported across the waste of waters, and as requiring 

 for their subsistence a pre-existing Fauna of some devel- 

 opment. They might be expected to make their appearance 

 along with the predaceous crustaceans ; as they do in the 

 uppermost Silurian rocks. 



And here, too, let us remark, that as, during this long 

 epoch we have been describing, the sea would have made 

 great inroads on some of the newly raised lands that had 

 remained stationary ; and would probably in some places 

 have reached masses of igneous or metamorphic rocks • 



