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Prof. Rogers thought that in the bursting of a rain drop 

 a similar process to that described by Mr. Desor might take 

 place. The drop might enclose a bubble of air beneath it, 

 which bursting would give rise to the appearances in ques- 

 tion. He thought the explanation of Mr. Desor very im- 

 portant, as indicating that the surface covered with these 

 impressions was subaqueous and not subaerial. 



Mr. Desor showed also sketches of foot-marks from the 

 same beach. 



The impressions bear a striking resemblance to certain foot- 

 marks in the new Red Sandstone of the Connecticut Valley, 

 where there is seen, besides the mark of the hind toe, an impres- 

 sion like that of the tarsal bone. But as there are no birds 

 (with the exception of some web-footed birds) that walk in this 

 way, those strange foot-marks have been ascribed to some kind 

 of reptiles. M. Desor said, that similar impressions are made 

 by the ravens when walking slowly and carelessly, as they do 

 over a beach. They then generally touch the soil with the nail of 

 their hind toe before they rest their foot, and thus produce an 

 impression which looks exactly as if it had been produced by the 

 tarsal bone. Sometimes, also, the raven, in raising the foot, 

 drags along the middle toe, and thus causes a very peculiar 

 track. 



M. Desor made, also, some remarks upon a layer of 

 Potsdam Sandstone from the falls of the river Saint Croix. 



It is filled with fossils, being for the most part Lingula and 

 Orbicula, together with some Trilobites. This stratum lies eight 

 hundred feet lower than that in which the species described by 

 Mr. Hall occur, and is therefore the oldest fossiliferous rock 

 known in the country. A specimen of it was presented to the 

 Society by Mr. Desor, on which there are seen a few specimens 

 of a species of Lingula described recently by Dr. Owen. 



Dr. Burnett read an essay on " Cell Types, as forming 

 the Bases of all the higher organic Types." 



The purport of the paper was to show the probability 



