J. E. Duerden — Jamaican Actiniaria : Parti. — Zoantheae. 365 



Palythoa caribsea, Duchassaing and Michelotti. 



(PL xvii. a, fig. 9.) 



Palythoa caribceorum, . . Duchassaing and Michelotti, 1860, p. 329. 

 Palythoa caribcea, . . . Duchassaing and Michelotti, 1866, p. 1-41, PL vi,, 



fig. 11. 

 Polythoa (Monothoa) caraibeorum, Andres, 1883, p. 322. 



Form. — Polyps smooth, rigid, cylindrical, closely associated and arranged in 

 an irregular manner, usually free from the ccenenchyme for a short distance, 

 free portion rounded or conical in retraction ; in very strong retraction, the 

 upper surface of the colony may be nearly flat; no wrinklings in specimens 

 preserved in formalin. Capitular ridges and furrows variable, usually from 14 to 

 17. The following numbers counted on two colonies will indicate the amount of 

 this variation : — 



A.— 15, 14, 16, 15, 14, 16, 14, 16, 15, 15, 15, 15, 14, 15, 15, 15, 15, 15, 15, 16, 15, 14, 

 16, 16, 17, 16, 17, 15, 14, 17, 15, 15. 



B.— 14, 18, 16, 14, 17, 15, 17, 17, 15, 17, 14, 15, 15, 14, 15, 14, 16, 15, 16, 16, 16, 16, 

 16, 17, 17. 



Tentacles dicyclic, smooth, pellucid, very short, acuminate, slightly entacmgeous, 

 inner row opposite capitular ridges, overhanging in full extension, vary from 28 

 to 34 in number. Disc considerably depressed in partial extension, overhanging 

 in full extension, cup-shaped or saucer- shaped, according to amount of extension ; 

 divisible into two portions : an outer, thin, transparent, non-incrusted, circular 

 area with rounded ridges and furrows corresponding to the number of tentacles, 

 and a dome-shaped central portion, with a few minute incrustations, and bearing 

 the slit-like mouth at the apex. 



The polyps are arranged very closely, and the amount of coenenchyme con- 

 necting the individuals is thin. At the periphery of the colonies, the outlines of 

 the different marginal polyps are clearly indicated. New individuals appear to 

 arise between previously existing ones. The colonies are usually very extensive, 

 irregular in outline, and often incrust very uneven surfaces, the height of the 

 polyps varying accordingly, so as to produce a regular undulating surface above. 



Colour. — In the living condition, a pale yellow or cream colour, or sometimes 

 brown, white when the ectoderm is rubbed off, lips white. In specimens preserved 

 in formalin a curious change is effected. Nearly the whole of the upper surface 

 of the colony may become a brick-red colour. The capitular ridges, however, for 



