CONTENTS OF VOL. XIll. 



No. I. — April, 1897. 



Pages 



Edwin Grant Conklin. 



The Embryology of Crcpidida, a Contribution 

 to the Cell Lineage and Early Development 

 of some Marine Gasteropods 1-226 



No. 2. — May, 1897. 

 A. D. Mead. 



The Early Development of Marine A^melids . 227-326 



No. 3. — May, 1897. 



I. J. Percy Moore. 



On the StmctJire of the Discodrilid Nephri- 



dinm 327-380 



II. Thos. H. Montgomery, Jr., Ph.D. 



Studies on the Elements of the Central Nerv- 

 ous System of the Heteronemertini . . . 381-444 



III. James R. Slonaker. 



A Comparative Study of the Area of Acute 



Vision in Vertebrates 445-502 



GINN & COMPANY, BOSTON, U.S.A. 



