Proceedings of the American Philosophical Society. 31 



method of placing the needles in pairs, over that which he has hitherto 

 employed, of keeping each needle separate from the other. A sugges- 

 tion also results in the use of the dipping needle, of the necessity of as- 

 certaining that the needles have, in the reversal of the poles, been charged 

 nearly, or quite, to saturation. The author takes occasion to correct his 

 statement in regard to the inefficacy of heating needles in boiling water 

 in producing an approach to a permanent magnetic state. The observa- 

 tions at each station, with the corrections employed, are given in tables; 

 and the numbers observed for the dip, or calculated for the horizontal or 

 total intensities, are compared with the results of other observers. 



The memoir concludes with the following abstract of the numerical 

 results. 



The committee, consisting of Mr. Nicklin, Prof. Bache, and Dr. Hays, 

 to whom was referred a paper, entitled " On the Patella Amaena of Say, 

 by Isaac Lea," reported in favor of publication, which was ordered ac- 

 cordingly. 



In this paper, Mr. Lea gives a synonymy, showing that the Patella 

 AmcBna of Say was first described by Miiller, under the specific name of 

 Testudinalis : Zool. Dan. p. 237 ; and Mr. Couthouy, having lately given 

 an elaborate description of the animal in the Boston Journal of Natural 

 Science, showing that it belongs to the new genus Patelloida, recently 

 established by Q,uoy and Gaimat d ; Mr. Lea argues that it should hence- 

 forth be called Patelloida Testudinalis. 



* Dip not observed. 



t Mean of results in June, July and August, 1837, and in July and August, 1838. 



