Page:Geology and Mineralogy considered with reference to Natural Theology, 1837, volume 1.djvu/241

 Rh the latter appearing, for the first time, after the total annihilation of many species and genera of a more complex character.

The prodigious number, variety, and beauty, of extinct Chambered shells, which prevail throughout the Transition and Secondary strata, render it imperative that we should seek for evidence in living nature, of the character and habits of the creatures by which they were formed, and of the office they held in the ancient economy of the animal world. Such evidence we may expect to find in those inhabitants of the present sea, whose shells most nearly resemble the 'extinct fossils under consideration, namely, in the existing Nautilus Pompilius, (See Pl. 31, Fig. 1,) and Spirula, (Pl. 44 Figs. 1, 2.)