294 Prof. Hitchcock on Ichnolithology^ or Fossil Footmarks. 



Batrachians. He regards them as having been produced by four 

 species. 



The first account of the fossil footmarks on the new red sand- 

 stone of Connecticut river, was pubhshed by me in 1836, in the 

 January number of the American Journal of Science. Seven 

 species only were described, of which five were three-toed, and 

 two species four-toed. Two species were pachydactylous, or 

 thick-toed, and five leptodactylous, or narrow-toed, the difference 

 between the two classes being very striking. These tracks were 

 boldly, perhaps rashly denominated Ornithichnites, or sio7iy bird 

 tracks. But when I came to give an account of a much larger 

 number of species, in my Final Report on the Geology of Massa- 

 chusetts, I changed this name to Ornithoidichnites, or tracks re- 

 semhling those of birds; and iSaurioidich7iites, or tracks resem- 

 bling those of Saiirians, as more in conformity with the cautious 

 spirit of true science than the former name. 



My Final Report was published in 1841; and having in the 

 four preceding years devoted much time and attention to the sub- 

 ject of footmarks, I was enabled to describe and figure of the nat- 

 ural size in that work, no less than twenty seven species. At the 

 meeting of the Association of American Geologists at Boston in 

 1842, I gave an account of five species more, and figures of these, 

 also of the natural size, were given in the first volume of their 

 Transactions. In the present communication I propose to describe 

 four species more, although I shall be obliged to strike two from 

 the previous list, so that the whole number of species which I 

 consider established to the present time, is thirty three. 



It was to be expected that when it was announced that bird 

 tracks, — some of them four times larger than those made by the 

 ostrich, — existed as low down as the new red sandstone, all geolo- 

 gists would receive the statement with great scepticism. They 

 would not have been true to their principles if they had suffered 

 any thing but the most overwhelming proofs to satisfy them. For 

 no trace of birds had hitherto been found deeper than the Wealden 

 formation. I was well aware, when I first published on the sub- 

 ject, with what incredulity my conclusions would be viewed. To 

 a person not familiar with the details of paleontology, there is not 

 any thing very remarkable in the statement, that birds existed at 

 the period of the new red sandstone, and left their footmarks on 

 its layers ; and accordingly, the community in general had only 



