66 PROCEEDINGS OF THE ASSOCIATION OF 



the existing species of birds most nearly resembling those sup- 

 posed to have made those tracks. 



As going to show llic inclined position of the strata at the time 

 when these impressions were made, Prof. W, B. Rogers called 

 attention to a peculiarity in the form of many of these impres- 

 sions, noticed by himself and Prof. H. D. Rogers in company with 

 Prof. Hitchcock, during the last summer, and often remarked by 

 Prof. Hitchcock on previous occasions. The feature referred to 

 resembles the effect of a slight sliding of the foot in soft clay. It 

 is seen in some of the larger footsteps, both those which point 

 upwards and downwards in reference to the present slope of the 

 rocks, and is even more conspicuous where the animal has been 

 walking horizontally along the inclined surface, in which case 

 there is a protuberance on the downhill side of each impression, 

 as if, in virtue of the slope, the pressure of the foot had accumu- 

 lated the soft clay in that direction. Adjourned to 



Thursday, 3J o'clock, p. m. — Prof. W. B. Rogers in the chair. 

 A communication from Prof. Chester Dewey on the polished 

 rocks of Rochester, N, Y., was read. 



Dr. Locke exhibited about eighty colored casts of the fossils 

 found in the western rocks, and offered remarks upon the advan- 

 tages to be derived to geological science from the distribution of 

 similar copies. 



Mr. James Hall and Prof. H. D. Rogers offered some remarks 

 on observations made in connection with Dr. Locke on the same 

 subject. 



Dr. King expressed the opinion that the fossils exhibited by 

 Dr. Locke, were not generally the same as those common to the 

 lead-bearing series of the upper Mississippi, and that from his 

 investigations, which had been pretty extensive, he believed that 

 the portion of the formation of that region in which the lead is 

 found, overlies, and is very distinct from what is considered by 

 Dr. Locke to be the cliff formation of Ohio. To this Prof. Locke 

 replied that the fossils presented by him, were not presented as 

 the fossils of that part of the cliff limestone, containing the lead 

 ore ; some of them were actually from the stratum overlying that 

 ore. 



Resolved, That the attention of the meeting be strictly confined 

 to the reading of papers, during the remainder of the present ses- 

 sion, and that no discussion be allowed thereon. 



Mr. James Hall read a paper in connection with a section 

 which he exhibited, of the rocks extending from Cleveland, Ohio, 

 southwesterly to the Mississippi. 



