March, 1842.] 155 



episcopalis, M. retusa, M. corrugata, M. aurantiaca, M. 

 melongena. 

 Oliva carneola. Conus capitaneus, C. stercus muscarum, C. 

 raphanus, C. magus. Phasianella angulata. Patella vulgata. 



Two specimens of Fossils from Gloucester county, N. Jersey, 

 a Sphirsena ? and a Buccinum. Presented by Dr. W. Bland- 

 ing. 



Written Communications. The chairman read a memoir 

 from Dr. A. Clapp of New Albany, Indiana, on the Lime- 

 stone formation of that district. Referred to a committee con- 

 sisting of Mr. Conrad, Prof. Rogers and Mr. Vanuxem. 



Verbal Communications. Prof. Johnson presented for 

 inspection, a portion of the kelson of the frigate Raritan, in a 

 state of dry rot. This vessel was still on the stocks at the 

 Philadelphia Navy Yarchher building having been commenced 

 at least 20 years since. She had been salted. Her lower 

 timbers, previous to the commencement of repairs, were 

 generally in the same condition as the portion exhibited. 



Also a sample of oak joist from the old Legislative Hall, 

 built at Chester, Pennsylvania, in 1682. Decay had not yet 

 commenced in this wood, owing probably to its complete pro- 

 tection from the action of moisture ; whereas in the other case, 

 the wood was constantly subjected to the alternate action of 

 dryness and moisture. 



Professor Johnson also alluded to the hardening influence 

 of water on oak wood when long submerged. 



Dr. Chaloner stated that he had in his possession specimens 

 of oak timber turned into various forms, which had been 

 derived from a vessel, (the Lyons frigate,) submerged in the 

 river Delaware since the period of theRevolution, and which 

 had acquired almost the hardness of iron. 



Professor Johnson then exhibited samples of residua from 



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