35 



M. H. Webster read a description of the Hystrix Dorsata, 

 or North American porcupine, with observations on its habits, 

 illustrative of a specimen in the Museum of the Institute. 



L. C. Beck continued the reading of his communication 

 on the lead mines of the Western States. 



March 2. The following donations were received : From 

 Solomon Van Rensselaer, iron pyrites and bituminous shale 

 from the vicinity of Albany ; from M. H. Webster, fossil 

 pectinites from the eastern shore of Chesapeake Bay ; fossil 

 turitella from Fort Washington, on the Potomac ; specimens 

 of the tertiary formation of Maryland; English silver Qoin 

 of 1786 ; from William Cooper, Maryland paper money, 

 1774. 



Simeon De Witt read a communication on the functions of 

 the moon, as deduced from the total eclipse of the sun on the 

 17th of June, 1806. 



Mr. De Witt also presented a drawing illustrative of the 

 appearance of the moon, during the above eclipse. 



D. M'Kercher read a paper on the natural history of the 

 black oxide of manganese, and its application in the arts. 



M. H. Webster read a description of a specimen of the 

 Unio Crassus of Say, var. Giganteus of Barnes, deposited in 

 the Museum by Dr. L. C. Beck. This specimen is a right 

 valve, and was obtained by the depositor on the banks of the 

 Illinois, where it is found in abundance. When compared 

 with the specimens described by Mr. Barnes, in 6 Silliman's 

 Journal, 118, it appears to be of much more magnificent di- 

 mensions. Of these the largest weighed fifteen ounces and 

 measured 



2.9 inches in diameter, 



diameter of posterior cicatrix, one inch, and depth, \ of an 

 inch. Dr. Beck's shell measures 



3.4 inches in diameter, 



4.7 " " length, 



7.7 " " breadth ; 

 its posterior cicatrix, 1 inch in diameter, and .3 of an inch in 

 depth— weighs 19 ounces. It was described as being, shell oval, 

 ponderous, rounded behind, angulated before, epidermis black- 

 ish brown, interior surface considerably waved, cardinal teeth 

 deeply sulcated, anterior cicatrix wrinkled and striated, nak- 

 ed, pearly white, iridescent. 



Mr. Webster also mentioned, that during the present sea- 

 son, Mr. James Eights had found three shells which were be- 

 lieved to be undescribed. One of these has subsequently been 



