CLYTIA. 141 



rooted by a creeping stolon ; hydrotlieca bell-shaped, with- 

 out operculum ; polypites with a large trumpet-shaped pro- 

 boscis ; gonothecce borne on the stolon and on the stems, and 

 producing free medusiform zooids. 



Gonozooid : Umbrella (at the time of liberation) almost 

 globular; manubrium short, ^-lipped; radiating canals 4 / 

 marginal tentacles 4, with bulbous bases, ivhich are not 

 ocellated ; lithocysts 8, two in each interradial space, borne 

 on the free margin of the umbrella. 



The number of tentacles and of lithocysts increases with 

 age, and the shape of the umbrella undergoes considerable 

 change. 



I FOLLOW Agassiz and Van Beneden in adopting Lamou- 

 roux's name of Clytia for the present section of the 

 Lainarckian genus Campanularia, which must be broken 

 up into several distinct groups. It is distinguished by its 

 somewhat deep-belled gonozooid Avith a comparatively 

 small number of arms, and with the lithocysts between the 

 tentacles and not upon them. The species that produce 

 free sexual zooids with a depressed umbrella and numer- 

 ous reentrant arms, and the lithocysts placed on the base 

 of the tentacles, must bear the name Obelia, which was 

 introduced by Peron and Lesueur in 1809. To the species 

 that are destitute of a medusiform zooid, Lamarck's old 

 and well-established designation, which was applied ori- 

 ginally to simple and branched forms alike, may be 

 assigned. 



The Laomedea of Lamouroux and Johnston was formed 

 to include the branched and tree-like as distinguished 

 from the simple and creeping species a division that does 

 not represent the natural affinities and cannot be main- 

 tained. In choosing between the various names that have 

 a claim to be retained for the new groups, I have thought 



