Table of Coiitents. 



Pag. 



Introduction 1 



Rcmaiks on tlie liteniture of recent times and on tlie foundation for a 



natural system 2 



The bathymetric distribiition of hydroids 8 



List of the North Atlantic Expedition Stations where Hych-oids were 



found 11 



Atliecata IB 



Fam. Corynidae !•> 



,, Tuhularidae 16 



,. Myriothelidae 31 



„ Clavidae ' 40 



Bougainvillidae 40 



,, Eudendridae 48 



Monobrachium i>l 



