J. E. Duerden — Jamaican Actiniaria : Part I. — Zoanthece. 359 



Drunhenman Cay : 



J.— 19, 18, 20, 18, 19, 19, 19, 20, 19, 19, 20, 20. 

 K.— 17, 17, 19, 18, 18, 17, 18, 17. 

 L.— 15, 20, 17, 16. 



Gun Cay : 



M.— 14, 16, 15, 16, 15, 14, 15, 14, 17, 17, 14, 14, 16, 14, 16, 12, 12. 



N.— 14, 14, 16, 15, 14, 15, 16. 



0.— 16, 16, 17. 



P.— 16, 16, 16. 



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



Maiden Cay : 



E.— 20, 18, 18, 16. 

 S.— 18, 19. 

 T.— 16, 16, 16, 17. 



From these it will be seen that, in the series represented by B, C, D, Gr, H, I, 

 J, K, R, S, the numbers vary from about 18 to 20, and in another, represented 

 by A, E, F, M, N, O, P, Q, T, the numbers are roughly from 14 to 17. The 

 average numbers of the capitular ridges of the two groups seem so constant 

 and distinct that I have considered them of sufficient importance to justify a 

 separation into the two accompanying species, and have found at the same time 

 other distinctions which further support the conclusion. Although the genus 

 occurs in such abundance around all the Cays, I have not found characters of 

 sufficient stability to warrant the separation of more than these two species. 

 Other diagnostic features will be discussed in dealing with their anatomy. 



Palythoa mammillosa (Ellis and Solander). 



(PI. XVII. a, figs. 7, 8.) 



Lapidis Astroitidis sive stellaris Sloane, 1707, vol. 1, tab. 21, figs. 1-3. 



primordia, 

 Alcyonium mammillosum, . . Ellis and Solander, 1786, p. 179, tab. 1, figs. 4, 5. 

 Palythoa mammillosa, . . . Lamouroux, 1816, p. 361, [pi. xiii., fig. 2. 

 Palythoa mammilosa, .... Milne-Edwards, 1857, p. 304.] 

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

 Palythoa mamillosa, .... Duchassaing and Michelotti, 1866, p. 140, 



pi. vi., fig. 10. 

 Palythoa cinerea, Duchassaing and Michelotti, 1866, p. 141, 



pi. vi., fig. 8. 

 Polythoa mammillosa, . . . Andres, 1883, p. 332. 

 Polythoa (Corticithoa) cinerea, . Andres, 1883, p. 323. 



