Academy ofNattiral Sciences of Philadelj)hia. 439 



stratum. I have here examined that which the author of the 

 Mecanique Celeste pubUshed in the Mem. Acad. desScienc. 1 818, 

 and afterward, in 1823, in the 11th booli o^ the Mecanique Ce- 

 leste; and I have shown its insufficiency to serve as the ground- 

 work of the theory of the figure of the planets. This sort of ana- 

 lysis, and even the method of demonstrating which the author 

 has chosen to adopt, have acquired some celebrity, and have 

 been applied in various researches ; and it seems to be of some 

 importance to the progress of mathematical knowledge, that 

 the grounds of it, and the limitations to wliich it is subject, be 

 well understood. For this reason I shall, on another occa- 

 sion, offer some additional remarks on this point before I pro- 

 ceed to the second branch of my subject. 



Nov. 30, 1825. James Ivory. 



[To be continued.] 



LXV. Repo7-t of the Transactions of the Academy of Natiu-al 

 Sciences of Philadelphia duriiig the Year 1824; submitted by 

 the Recording Secretary, in pursuance of a Resolution of the 

 Academy. 



[Concluded from p. 354.] 



§ 2. Geology atid Organic Remains. 



T^HE intimate relation which exists between the study of 

 ■'• the structure of the earth, and that of the remains of a 

 former world which are seen in many of its strata, requires 

 that the examination of fossil remains, whether animal or ve- 

 getable, should be always kept connected with the observa- 

 tions upon the mineral composition of our globe itself. 



Seven communications were received in this department of 

 science. The first, which is entitled " Description of a testa- 

 ceous formation at Anastasia Island, &c. by R. Dietz," de- 

 scribes a very singular rock, of which Mr. Dietz brought home 

 many specimens last year, and which had attracted the atten- 

 tion of our geologists, being almost entirely composed of frag- 

 ments of various shells agglutinated together. Mr. Dietz 

 states that Anastasia Island, situated opposite to St. Augustin, 

 along the coast of East Florida, has a considei'able portion of 

 its northern, and perhaps the substi'atum of the remaining part 

 of the island, formed entirely of this interesting aggregate, in 

 which Mr. Say has recognised fourteen different species of 

 shells belonging to the genera Area, Mactra, Dotiax, Crepidula, 

 Lucina, Natica, Oliva, Nassa ,• the three first constituting nearly 

 the whole mass of the rock, — of each of tlie other genera one 

 individual alone having been observed. Mi*. Dietz offers a 



theory 



