XXII. 

 STUDIES ON THE EMBRYOLOGY OF THE SIPUNCULID^E. 



I. THE EMBRYONAL ENVELOPE AND ITS HOMOLOGUE. 



(PLATE XXXII.) 

 John H. Gerould. 



MARINE BIOLOGICAL LABORATORY. 



Received /^, ^V f 



Accession No. -' J 



Given by C^CC If ^Wfldl 



Place, 



***No book op pamphlet is to be removed from the lab- 

 oratory tuithout the permission of the Trustees. 



