64 PROCEEDINGS OF THE AMERICAN ACADEMY 



in Carcharias and full in Carcharodon, though a careful com- 

 parison will reduce the number of established species of fossil 

 Carcharodons. He had also discovered new genera oi S cedes. 

 Of the three fossil genera, Myliobates, Zygobates, and Aeto- 

 bates, the first is found living in the Old World, while the sec- 

 ond and third are unknown there, except as fossils ; all these 

 genera have been found living in North and South America. 

 Of the genus Raia, of which there are vast numbers in Eu- 

 rope, the number is diminished in America by at least one 

 third. 



Professor Peirce made a communication on a new view of 

 the fundamental principles of Analytic Mechanics. 



Three hundred and eiglity-eiglith meeting. 



November 17, 1853. — Adjourned Quarterly Meeting. 



The President in the chair. 



The time of this meeting was occupied in the transaction 

 of business. 



A communication was received from Mr. C. O'Brian, re- 

 questing permission to publish in a scientific periodical, about 

 to be established in Cambridge, the proceedings of the Acade- 

 my. The communication was referred to the Committee of 

 Publication. 



Three hundred and eighty-ninth meeting. 



November 29, 18.53. — Second November Meeting. 



Dr. Charles Beck in the chair. 



Dr. Burnett made a communication on the development of 

 organs, especially of those of glandular structure ; in which 

 he traced the progress from a mass of cells, arranging them- 

 selves in linear series, through the various stages of lateral 

 saccations or diverticula, and the dichotomous ramifications 

 dividing and subdividing to form the intricate structure of the 

 organs. For instance, the ureter, first formed, undergoes this 

 multiplied ramification till it forms the glandular structure of 



