176 GENUS ZOANTHUS. [December. 



Inhabits the madrepore rocks, at the bottom of the 

 bay of St. Thomas, united in large groups. 



It was my intention to class all the animals described 

 in this paper under the generic title of Actinia; but I have 

 since thought it expedient to arrange the three following 

 species under the genus Zoanthus, instituted by the Che- 

 valier Cuvier, in his excellent work, recently published, 

 Le Repine Animal. The following are the characters laid 

 down by this author: 



Genus ZOANTHUS. 



The animals of this genus have the same fleshy skin, 

 tlie same disposition of mouth and tentacula, as those of 

 the Actinia; they have likewise an organization nearly 

 similar; but they are united in numbers more or less con- 

 siderable, on a common base", sometimes in the form of 

 creeping roots, sometimes spreading over a large surface. 



1. Z. sociata. Tentacula numerous, yellow, short; 

 disc greenish; peduncle very long and slender, and of a 

 violaceous brown colour. 



The body of this species is smooth, slightly striated 

 longitudinally, and transversely, by the nuisclcs; the ten- 

 tacula are smooth^ placed in two rows, and about sixty in 

 miniber; mouth small, linear. 



The animals of this species reside in communities, 

 united by the base of their peduncles, on a tube or root, 

 which penetrates below rocks; and they extend their discs 

 in the interstices, on a line with the common surfoce. 



Inhabits Guadaloupe. Perhaps this species is the A^ 

 sociata of Ellis and Solandcr; page 5, pi. 1. fig. 1. 



