822 ANNUAL OF SCIENTIFIC DISCOVERY. 



well, at a depth of fifty feet below high-water mark, showing the great 

 inequalities of the ancient sea bottom. With regard to the species 

 found at Point Shirley, Mr. Stimpson remarked that those most com- 

 mon in this deposit are inhabitants of deep water, and of northern 

 origin. With one exception they may all be obtained in a living state 

 by dredging within a mile of the locality where they are now found 

 fossil. 



The state in which they occur would seem to furnish evidence in 

 favor of Lyell's theory of the drift being deposited from the melting of 

 icebergs, by which the materials had been transported. The shells are 

 almost invariably broken, but not worn, their angle of fracture remain- 

 ing sharp. 



Mr. Desor said that it had been thought that the coarse drift near 

 Boston was glacial in its origin. The fact that shells had been found 

 in it had been offered as an objection. This had been explained by 

 the supposition that a glacier had entered the sea at the point where 

 the shells had been found in the drift. The existence of a layer of 

 clay containing shells beneath the coarse drift at Point Shirley, would 

 seem to indicate a quiet deposition at variance with the glacial theory. 



