CONTENTS OF No. 3, DECEMBER, 1891. 



Pages 

 I. On the Osteology of Mesohippus and Leptomeryx, 



with observations on the modes and factors of 



evolution in the Mammalia. W. B. Scott . 301-406 



II. The Growth and Metamorphosis of Tornaria. 



T. H. Morgan 407-458 



III. A Human Embryo twenty-six days old. F. 



Mall ..''...', 459-480 



IV. On the Precocious Segregation of the Sex-Cells 

 in Micrometrus Aggregat?cs, Gibbons. Carl 



H. ElGENMANN 481-493 



V. Some Points in the Development of the Toad- 

 Fish (Batrachus Tau). Cornelia M. Clapp 494-502 



VI. Development of the Epiphysis in Coregonus 



Albus. Charles Hill 503-510 



VII. Notes on the Development of some Sponges. 



Henry V. Wilson 51 1-5 19 



Typography by J. S. Cushing & Co., Boston, U.S.A. 

 Presswork by Ginn & Co., Boston, U.S.A. 



