116 [Decembeu, 



casts of Sivalik Fossils lately presented by the Hon. E. I. Company to 

 the Academy, which had been mutilated in the transportation, would 

 be replaced by others, which were already in course of preparation. 



A communication was read from the Secretary of the American 

 Philosophical Society, dated October 21, 18-i8, acknowledging the 

 receipt of No. 2, New Series, of the Journal of the Academy. 



J^ovemher 28t/i, 184-8. 

 Mr. Vauxiu the Chair. 



The Committee appointed to superintend the printing of the New 

 List of Members and Correspondents, reported that they had performed 

 that duty, and that copies were ready for distribution. The List com- 

 prises the names of 70 life members, 80 contributing do., 33 non- 

 contributing do., and 62 deceased do., total 245 ; and of Correspon- 

 dents, foreign 257, (42 deceased) and domestic 263, (45 deceased) 

 total 520. Total Members and Correspondents to Oct. 1, 1848—765. 



The Committee to whom was referred Professor Johnson's letter in 

 reference to a memorial to Congress recommending the addition of one 

 or more Naturalists to the Astronomical expedition now being fitted out 

 for Chili, by order of the Government, i?e;;or/e(/, that they consider this 

 addition as of great importance, and would recommend the appoint- 

 ment of a Committee, with authority to take such steps in the matter 

 as may be necessary to ensure this result. Report adopted, and on 

 motion, the whole subject was referred to the same Committee, viz ; 

 Dr. Morton, Dr. Bridges, and Mr. Vaux. 



December 5th, 1848. 



Mr. Phillips in the Chair. 



A letter was read from the Secretary of the Smithsonian Institute, 

 transmitting the first volume of their " Contributions to Knowledge," 

 with a Circular describing the plan of organization of the Institution, 

 and a printed list of queries addressed to the Librarian of the Academy 

 in relation to the Library. 



A letter was also read from the Imperial Society of Naturalists of 

 Moscow, dated August 17, 1848, accompanying several numbers of 

 the Bulletin of that Society. 



Dr. Leidy offered the following observations on the development of 

 bone, the structure of articular cartilage, and on the relation of the 

 areolar tissue with muscle and tendon. 



1. 071 the development of the Purkinjean corpuscle in lone. — Schwann, in his 

 «' Mikroskoplsche Untersuchuiigen," considers that the Purkinjean corpuscle of 

 bone is derived from the pre-existing cartilage cell, and that the canaliculi are 

 prolongations, or protrusions of the cell wall. Many later authors, among whom 

 are Gerber, and Todd and Bowman, express the opinion that it originates in the 

 nucleus of the temporary cartilage cell, and Tomes entertains the idea, that after 

 the formation of the osseous tubes, in the process of ossification, the latter are 



