314 Prof. Hitchcock on Ichnolithology, or Fossil Footmarks. 



formed and preserved. But the whole history of the rain-drops de- 

 serves a separate communication, and a more careful collection 

 of specimens than has yet been made. Suffice it to say in this 

 place, that these impressions are quite common at many of the 

 localities of footmarks, though not in them all. Large slabs can 

 sometimes be obtained beautifully filled. 



Some facts connected with the footmarks of the Connecticut 

 valley, throw light upon the question whether the sandstone on 

 which they are found has been tilted up since its deposition. 

 But this subject will be more conveniently and pertinently intro- 

 duced in another paper, which I propose to present to the Asso- 

 ciation. 



Supposed Footmark on the Slate of Hudson River. 



I now advance to a part of my subject which will probably 

 be received with more hesitation than the positions already pre- 

 sented. In the year 1837, I suggested, in the American Journal 

 of Science, that I had found some marks on the flagging stones 

 of the city of New York, which might have been made by a 

 didactylous quadruped. In company with W. C. Redfield, Esq. 

 I visited very many of the streets of New York and Brooklyn, 

 where the rock containing the supposed tracks is extensively 

 used in the sidewalks ; but the impressions were not found to 

 be numerous, though occasionally to be met with. I obtained 

 liberty to remove the best slab I could find, which was twenty 

 eight by forty four inches, and it is now in my cabinet. How- 

 ever, upon re-examination I became sceptical in regard to my 

 fi.rst views of the impressions, and I feared, also, that by bring- 

 ing forward what appeared to myself a doubtful case, I should 

 render the community still more incredulous in regard to the 

 Ornithichnites ; so that I judged it best to say no more about the 

 New York impressions. Still the idea has always haunted me 

 that they must be the result of organic agency ; and a re-exam- 

 ination of them recently has so satisfied me on this point, that 

 I venture, with no little diffidence, to bring the case before the 

 Association. 



The rock that contains these impressions is quarried in im- 

 mense quantities for flagging stones in the counties of Ulster, 

 Greene, and Albany. It belongs to the Erie division of rocks, 

 as they are called in the New York geological survey, and as 



