Haddon and Shackleton — Admice : I. Zoanthece. 691 



PALYTHOA, Lamx., 1816. 



Corticifeea, Lesueur, 1817. Polythoa, Andres, 1884. 



Mammillifeea (pars), Blainville, 1830. Polythoa (Corticithoa), Andres, 1884. 



Brachycnemic Zoanthese with a single mesogloeal sphincter muscle. The body- 

 wall is inci'usted. The ectoderm is continuous (?); the mesogloea contains numerous 

 lacunae, and occasionally canals. Dioecious. Polyps immersed in a thick coenen- 

 chyme, which forms a massive expansion. 



The genus Palythoa was founded by Lamouroux (1816, p. 359) for the 

 reception of two species which had previously been described and figured by Ellis 

 and Solander as Alcyonium mammillosum and A. ocellatum (1786, pp. 179, 180, PI. i., 

 figs. 4—6). Palythoa is thus defined by Lamouroux: — " Polypier en plaque 

 dtendue, couverte de mamelons nombreux, cylindriques, de plus d'un centimfetre 

 de hauteur, rdunis entre eux; les cavit^s ou cellules Isoldes, presque cloisonndes 

 longitudinalement et ne contenant qu'un seul polype." 



PalytJioa mammillosa is evidently regarded by Lamouroux as the type species 

 of the genus. He reproduces Solander's figure of this species, but not that of 

 P. ocellata, of which he merely gives a description. Unfortunately a Latinized 

 version of the French name " Palythod Etoillde," given by Lamouroux to P. 

 mammillosa, has been added at the bottom of his plate — a circumstance which has 

 given rise to some confusion. 



In 1817 Lesueur, being evidently unacquainted with Lamouroux's work, 

 erected the genus Corticifera for two West Indian species which he named C. gla- 

 reola and C. flava. These species are evidently very nearly allied to P. mammillosum 

 and P. ocellata : indeed Lesueur queries whether C. flava is not synonymous with 

 Alcyonium ocellatum, Ellis and Sol. ; and his definition of the genus Corticifera 

 agrees very nearly with that of Lamouroux for Palythoa. 



Subsequent naturalists have, with very few exceptions, recognized the priority 

 of Lamouroux's genus, and have applied the name Palythoa to all those Zoanthese 

 which are incrusted with sand, and are immersed to a greater or less extent in the 

 coenenchyme, forming corticiferous expansions. In this sense Verrill used the 

 term in 1869, and Hertwig in 1882 adopted the same classification. 



Unfortunately the genus Palythoa has also been occasionally extended to 

 include Zoanthese which are incrusted with sand, but which are united only at the 

 bases, forms which are included in the genus Epizoanthus, as defined by Verrill 

 (1869, p. 437). Amongst the species to which the name Palythoa was thus 

 mistakenly applied was a form with ribbon-like coenenchyme and exsert polyps, 

 described by Schmidt as P. azinellce (1862, p. 61). 



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