170 NEW YORK STATE MUSEUM 



transverse sections of the Orthoceras appear as circular or 

 oval discolorations elevated or depressed and are known to the 

 quarry men as "knots." In no instance have I noticed any marked 

 deviation in the position of these long, straight cephalopod shells 

 from the vertical, nor are they oriented otherwise than with the 

 apexes down and apertures up. 



We have then here layers of sand, deposited in a shallow, 

 retired sea or arm of the sea at a depth and under condi- 

 tions extremely unfavorable for the development and growth 

 of true marine life, crowded with innumerable thousands of 

 these cephalopods in this most peculiar and unexpected atti- 

 tude. As to the cause of this occurrence, one fact seems 

 perfectly clear, that these shells have been borne in by the 

 waves from deeper waters, as it is well established that 

 Orthoceras, like most of its heavily shelled allies, was a ben- 

 thonic animal. These remains must also have been floated in as 

 dead shells, but their position with the apex down is not easy to 

 account for unless we conceive that the early chambers had been 

 broken into and more or less filled with mud or isand. As to the 

 source whence they came, it may be said that, though these 

 fossils have not clearly retained specific characters, an Ortho- 

 ceras of similar large size and general proportions is occasion- 

 ally found in the fauna of the Ithaca group which occupied the 

 province immediately to the west during the deposition of the 

 Oneonta beds. 



In the discussion of this problem before the geologic sec- 

 tion of the American association at its Columbus meeting 

 (1899) it was suggested that a sudden incursdon of fresh water 

 from the continental drainage way 'into the marine province 

 occupied by these Orthocerata would be a sufficient cause 

 for the sudden and immediate extinction of their life. I should 

 regard this as a probable explanation of that general and wide- 

 spread destruction. Such a cause would have annihilated all as- 

 sociated marine life, and it is evident that the Orthocerata 

 have been carried well away from their habitat by flotation after 

 death. With the apical chambers of the shells weighted with 



