320 



I'unning into it comes from some twenty or thirty acres of meadow, from 

 a hundred yards to a quarter of a mile distant, and a few feet (less than 

 ten apparently) higher level. Now the pond, when it existed, was too 

 deep for the growth of peat-forming plants, and not favorable for the 

 growth of Diatoms in any large quantity. But the meadows above 

 were, particularly before the cultivation of the country, and the intro- 

 duction of artificial drainage, most favorable for the growth of Diatoms. 

 The sluggish stream draining the meadows would have force enough, 

 especially in floods, to wash out the Diatoms, and not enough to move 

 sand : neither could the meadows supply sand. When the Diatoms 

 reached the pond, they would of course settle to the bottom ; for the 

 mass of water in the pond being so great in proportion to the supply 

 there would be no perceptible current in it. In fact, it was a per- 

 fect natural trap for the Diatoms, in principle exactly like the process 

 used for separating Diatoms from sand and other coarse material, in 

 mounting for the microscope. The course of the little stream running 

 into the pond, is for a few rods through a ridge of drift material. This 

 undoubtedly furnished some sand and coarse material, but it would be 

 deposited almost immediately on entering the quiet water of the pond, 

 and undoubted!}' it will now be found directly against the entrance of 

 the stream. 



After the examination of this place, the conclusion must be that this 

 deposit has been forming ever since the close of the drift period, when 

 the surface of the earth received its present conformation. 



The Chairman announced the sudden death of Dr. George 

 Hayward. He was one of the members of tlie old Linnean 

 Society, and, when that dissolved, became one of the ac- 

 tive founders of this Society, was one of its earliest Vice- 

 Presidents, and had always taken a deep interest in its 

 progress. 



The following letters were read, which had been recently 

 I'eceived, viz : — 



From the Naturhistorische Gesellschaft zu Hannover, March 1st, 

 1863, from the Natural History Society of Dublin, August 5th, 1863, 

 and the Societe Entomologique de Belgique, Bruxelles, August 31st, 

 1863, asking for an interchange of publications. From Francis W. 

 Lewis, M. D., Philadelphia, May 22d, 1863, Dr. John J. Craven, U. S. 

 v., Hilton Head, June 24th, 1863, and Dr. William O. Ayers, San 

 Francisco, July 24th, 1863, acknowledging their election as Corre- 

 sponding Members. 



Mr. C. T. White was elected a Resident Member. 



