79 



Natica heros. Apparently not so plenty as iV! dupUcata, which 

 is the more soutliern species. 



Pyrula canalicidata. — Wrinkle. This is about the northern 

 bountlary of this species. It goes to Charleston, S. C, to Florida, 



&c. 



Mya arenaria, is sometimes cast alive, by the tide, into ditches. 



Polynoe. Found among sea-weed. The scales on the back 

 come off very easily. 



Hydractinia, in great beauty and plenty. Incrusting such 

 dead shells as move ; i. e., those of hermit-crabs. There were 

 observed medusae buds on them. 



Dr. Kneeland presented a specimen of Cordiceps Caro- 

 linensis^ from West Roxbury, Mass., in which the fungus, 

 two inches long, grew from the under surface of the cater- 

 pillar between the head and the first segment of the body. 

 Also specimens of the apple and peach borer, from Little- 

 ton, Mass. 



Mr. Stodder read a paper from Mr. Arthur M. Edwards, 

 of New York, 



ON THE DIATOMACEOUS FORMS CONTAINED IN A PEAT MARL 

 FROM MILAVAUKEE, PRESENTED TO THE SOCIETY ON MARCH 



16, 1859, 



Having been requested by Charles Stodder, Esq., to make a 

 microscopical examination of a specimen of " Peat marl," from 

 Milwaukee, I herein present the results : — 



The marl is of a gray color, and much charged with calcareous 

 matter, resulting from the freshwater shells deposited with it, 

 many of the smaller species of which still remain entire. On act- 

 ing on it with strong boihng nitric acid, everything is dissolved, 

 except the silica present either as sand or the shells of Diatoma- 

 ceae, leaving an almost colorless residue. When this is examined 

 by means of the microscope it is found to consist, for the most 

 part, of the remains of freshwater Diatoms, associated with sand 

 and spicules of freshwater sponges in small quantity. This marl 

 is apparently of recent formation, and belongs to the class of de- 

 posits in the course of deposition at the bottom of all our ponds 

 and lakes. 



