350 PROCEEDINGS OF THE ACADEMY OF [1892. 



November 8. 



The President, General Isaac J, Wistar, in the chair. 



Fifty-four persons present. 



Papers under the following titles were presented for publication : — 



" Contributions to the Life Histories of Plants, No. 8." By- 

 Thomas Meehan. 



" Preliminary Outline of a New Classification of the Helices." 

 By H. A. Pilsbry. 



Note on the Geology of Mt. Desert Island. — Dr. Henry C. 

 Chapman exhibited remains of a Brachiopod, Spirifer mucronota, 

 of an Ophiuran, Ophioden sericetim, and Yoldia glacialis given by 

 Charles S. Dorr, Esq., of Boston, to the Academy The specimens 

 were obtained from clay in digging a well at " Old Farm," Bar Har- 

 bor, Mount Desert, Maine. Dr. Chapman stated that as far as he 

 knew, with the exception of the remains of lowly organized forms 

 of marine life found in the clay at Seal Harbor, these were the 

 first fossils found at Mt. Desert. He referred incidentally to the 

 discontinuity of the granite axis of the island, the intervals 

 between the mountains being more or less filled up with water as 

 seen at Jordan's Pond, Long Pond, Echo Lake, etc. Allusion 

 was also made to the difiiculty in determining the relative age of 

 the flags, argillaceous shales and arenaceous schists deposited 

 upon the flanks of the island, as at Bar Harbor, Schoonerhead and 

 elsewhere. This is owing to the fact that in all such cases the deposits 

 lie directly upon bed rock and are never superimposed on each 

 other. 



November 15. 



Mr. Lewis Woolman in the chair. 



Fifteen persons present. 



Diffuse pigmentation of the epidermis of the oyster due to 

 prolonged exposure to the light : regeneration of shell and loss 

 of adductor muscle. — Prof. Ryder re])orted on behalf of Prof 

 il. C. Schiedt that oysters which had the right valve re- 

 moved and exposed to the light in this condition, in a living 

 state for a fortnight or so, developed pigment over the whole of the 

 epidermis of the exposed right mantle and on the upper exposed 

 sides of tlie gills, so that the whole animal from this cause assumed 

 a dark-brown color. Animals so exposed not only attempted to 

 reproduce the lost valve and hinge, but also partly succeeeded in so 



