PROGRESSIVE DEVELOPMENT OF ORGANIC LIFE. 211 



such an operation, for the land beneath the former sea has been laid 

 bare, and is now exposed, over an extent equal to that of all the 

 habitable parts of the globe. Every island and continent has formed 

 part of an ancient bed of the ocean, and that not once, but repeat- 

 edly. This extended surface of the ancient bed, is exposed to the 

 examination of thousands of observers, in every degree of latitude 

 not covered by polar snows. The absence of remains of the higher 

 orders of animals in all the secondary strata, and the frequent re- 

 currence of these remains in the more recent or tertiary strata, ap- 

 pear to afford presumptive evidence, amounting almost to certainty, 

 that the higher orders did not exist, at least in the northern hemis- 

 phere, till an epoch subsequent to the deposition of all the seconda- 

 ry formations. 



When we ascend to the strata deposited at a later period than 

 chalk, we find a remarkable change in the character of the organic 

 remains. The ammonites, and other chambered shells, which are 

 so numerous in the secondary strata, disappear, entirely, in the ter- 

 tiary strata, except the fossil nautilus, which is occasionally found in 

 them ; and the animal now exists as a living species in the Indian 

 Ocean. The enormous lizards, and animals allied to the lizard and 

 crocodile, whose bones abound in the secondary strata, from lias to 

 chalk, disappear also in the tertiary strata, with the rare exception of 

 a small species of crocodile ; — a fact which indicates, that animals of 

 this order ceased to be inhabitants of northern latitudes when the 

 tertiary strata were deposited. In the tertiary strata, the place of 

 these enormous reptiles is occupied by the remains of the higher or- 

 der of terrestrial mammalia, but belonging to genera or species now 

 extinct; the gigantic mastodon, the mammoth, and megatherium, 

 rivalled in magnitude the enormous reptiles of a more ancient world. 

 Other species of mammalia of less size, both herbivorous and car- 

 nivorous, but equally perfect in their organization with the land quad- 

 rupeds of the present epoch, have left their bones in many of the 

 tertiary beds. Here we may stop ; for we approach to a period 

 connected with the present order of things, a period immediately 

 preceding that mysterious operation of divine power and intelligence, 

 the creation of jnan. 



The doctrine of the progressive development of organic life here 

 briefly stated, has been recently opposed by highly ingenious argu- 

 ments, which display the great talents and ability of the author, but 

 which, in my opinion, do not invalidate the truth of the doctrine, — 

 a doctrine, however, that, like almost all general conclusions, requires 

 to be admitted with certain limitations and^fsstrictions. Every in- 

 stance hitherto adduced, of bones of the f^igher orders of animals 

 being found in ancient secondary strata, has proved, on accurate ex- 

 amination, to be fallacious. An instance of this kind came under my 

 observation, when on a visit to my native town, Nottingham, in J 831. 

 A medical gentleman showed me the portion of the thigh-bone of 



