﻿ANNIVERSARY ADDRESS OF THE PRESIDENT. Ivii 



reached me, I had satisfied myself of the genuineness of the reptilian 

 foot-prints, first observed in 1844 by Dr. King at Greensburg in 

 Pennsylvania, and which I examined carefully in his company in 

 1846*. They occur as casts on the lower side of slabs of sandstone, 

 in the midst of the coal-measures, and were evidently made by a 

 large air-breathing animal, walking over soft mud which afterwards 

 dried and cracked in consequence of shrinking. This American 

 fossil appears to have been a much broader animal than the European 

 triassic Cheirotherium and of a different genus. Its stratigraphical 

 position is unequivocal, as it is imbedded in coal-measures containing 

 impressions of Lepidodendron, Sigillaria, and Stigmaria, some of the 

 plants being specifically identical with those of the European coal. 

 I alluded in my last Anniversary Address to other foot-prints of a 

 large reptile, supposed to be of considerably older date, found in 

 1849 by Mr. Isaac Lea, in red sandstone referred to the Devonian 

 period, at Pottsville, near Philadelphia. These appear to be referable 

 to a different species, and have been lately shown by Prof. H. D. 

 Rogers to belong to the lowest part of the carboniferous series, and 

 are therefore not much more ancient than the foot-prints of Greens- 

 burg, above mentioned. 



In the course then of the last six years, memorials of reptile life 

 have been traced back from the Permian to the bottom of the Car- 

 boniferous deposits, or nearly as far as any land-plants, and farther 

 than the oldest land-shells, yet known. They have been carried 

 down as it were, in six years, through a voluminous series of docu- 

 ments 15,000 feet or more in thickness ; and we ought therefore by 

 no means to despair of tracing birds or any other inhabitants of 

 the land to periods as remote. 



I will now proceed to consider the bearing of the organic remains 

 of the secondary formations, from the trias to the chalk inclusive, on 

 the doctrine of successive development. Respecting the Invertebrata 

 of this vast period, I need only say, that memorials of all the aquatic 

 tribes are as abundant as we could expect to find those of living in- 

 vertebrata in the bed of the actual seas. But it is worthy of notice, 

 that the freshwater and terrestrial mollusca are usually, as in older 

 formations, very rare or entirely wanting. No helices or other land 

 shells have been collected, for example, from the lias, although Mr. 



* See the Author's Second Visit to the United States, vol. ii. p. 305. 



