CONTENTS. 



Ctenophora. 



Page 



Introduction I 



I. Tjalfiella tristorna Mrtsn 3 



A. Anatomy and Histology of the grown animal 5 



B. Development; Anatomy of the Cydippid-stage if, 



C. Regeneration 2 , 



D. Affinities of Tjalfiella 25 



E. Phylogeny 37 



II. The pelagic Ctenophora of the Northern Atlantic 60 



1. Mertensia ovum (FabriciusJ 60 



2. Pleurobrachia pileus (O. F. MulL) 68 



3- crinita Moser ~. 



4. Bolina infundibulum (O. Fr. Muller) 75 



5. Beroe cucumis Fabricius g, 



Hormiphora plumosa (M. Sars) gg 



Lesueuria vitrea M. Edw gq 



Cestus veneris Lesueur. n r 



Beroe Forskalii Chun g2 



Zoogeographical Remarks g2 



58800 T 



