AMERICAN GEOLOGISTS AND NATURALISTS. 23 



ations too remote from present oyster beds to have been made 

 by human agency, such as those in Cumberland county, in New 

 Jersey ; therefore it would appear that both causes have operated 

 to produce them, and that no single generalization can comply with 

 the requisition of the facts which are presented, leading as they do 

 to a two-fold one from opposite conclusions, one referable to human, 

 the other, to natural causes ; and that severally they must be exam- 

 med in order to ascertain to which of the two causes any given 

 mass is to be referred.* 



Lardnek. Vanuxem. 



Prof. Booth stated that his observations upon these deposits 

 had led him to the same conclusion as that which had been arrived 

 at by JVIr. Vanuxem, namely, " that they are sometimes referable 

 to human agency, and at others to natural causes." In answer 

 to an inquiry. Prof. B. observed that these shells reduced to pow- 

 der had been used with great success in the State of Delaware, 

 as a manure. Prof. Hitchcock stated that the fertilizing powers 

 of these deposits of shells had also been tested by experiments 

 on Cape Cod. Facts were stated by the chairman and Prof. 

 Mather in regard to beds of oyster shells similar to those describ- 

 ed by Mr. Vanuxem, on the Island of Nantucket, and on Long 

 Island. 



Prof. Bailey commenced his account of " Fossil Infusoria," 

 by an exhibition and description of the microscope employed by 

 him in his researches. 



Messrs. Charles B. Trego and B. Silliman, Jun. were ap- 

 pointed assistant secretaries. The Association then adjourned 

 until nine o'clock, Thursday morning. 



Third day of meetings Thursday, April 8, 1841. — The Asso- 

 ciation met at nine o'clock, a. m. Prof. Silliman in the chair. 

 The minutes of yesterday were read and adopted. 



Peter A. Browne, Esq. laid on the table, for the inspection 

 of the members, a suite of specimens, chiefly fossils, from the 

 chalk basin of Paris, collected and labelled by A. Brongniart. 



Prof. Locke made some observations concerning the connec- 

 tion of magnetism with geology, mentioning an instance where 

 he found an increase of the dip and intensity as he approached, 

 from south to north, a certain point or meridian line, and a de- 



* Since the meeting of the Association, I have found on conversing with Dr Ducalel 

 that the impressions which I had of his views were founded upon his first report, tiiat of 

 1S34, for in his subsequent ones, he makes known their two-fold origin. We should 

 withdraw this paper did we not believe that it would be of service ; for it not only settles 

 the point in question, which was its object, but it affords a useful lesson as to caution in 

 expressing the opinions of others. 



