98 PERCY SLADEN TRUST EXPEDITION 



Hebrides, it appears lie was dealing with two specimens ; of these only one (incrusting 

 corallum, measuring 5*5 X 5 cm.), presumably the smaller, was found in the British Museum. 

 It is not in any case a Goniastrea, but comes nearest the present species. 



Of PlesiastrcBa haeckeli, Brligg., I have seen only two or three corallites, kept in the 

 Berlin Museum ; they are similar to those of Prionastrcea melicerum, Ed. and H. 



Localities. Maldives : Hulule (6) ; Addu (5 small and 1 from 25 fms.) ; Suvadiva 

 (1 small, 25 fms.). Minikoi (2). Seychelles (4). Saya de Malha (1 small, 29 fms.). 

 Cargados (1 small, 30 fms.). Chagos, Salomon (7). 1 Amirante (1, 16 fms.). Providence 

 (I, 29 fms.). Also from Eed Sea (Ehrenberg, Milne Edwards and Haime, and Klunzinger), 

 ? New Hebrides (Quelch), ? East Indies (Michelin), ? (Esper). 



8. Favia ananas, Ellis and Solander. (PL 10, figs. 2 and 4 ; 25, fig- 7.) 



1786. Madrepora ananas, Ellis and Solander, Nat. Hist. Zooph., p. 168, pi. 47, fig. 6 (non Astrea ananas, 



Lamarck). 

 1857. Flesiastrcea peroni, Milne Edwards and Haime, Hist. Nat. CoralL, ii, p. 492, pi. D7, fig. 3a and b. 

 ? 1866. Plesiastrea indurata, Verrill, Proc. Essex Instit., vol. v, part 3, p. 35, pi. 2, fig. 7. 



Corallum. Massive. Corallites circular or oval, with distinct rims. Walls about 

 1 — 1'5 mm. thick, meeting in polygonal inter-corallite furrows. Calices 4"5 — 5 mm. in 

 diameter, about 4 mm. in depth. 



Septa thickened towards walls, vertical, with entire or serrate edges, slightly rough 

 sides, exsert to 1 or 1"25 mm., 21 — 24 in number; of these 8 — 11 meeting columella, each 

 usually with a blunt somewhat thickened paliform lobe. An alternating cycle of 

 rudimentary septa present. Costse of main septa conspicuous, with transversely extending 

 granulations, those of rudimentary septa smaller ; the former meeting latter or the costse 

 of the main septa of adjacent corallites in inter-corallite grooves. Columella low, loosely 

 trabecular, \ — \ width of calyx, sometimes quite rudimentary. Multiplication by fission. 

 Polyps. (1) Both entocoelic (only over principal entocoeles) and exocoelic tentacles 

 present. (2) Stomodaeal ridges thicker than broad, with convex inner surfaces. (3) Seven 

 principal couples of mesenteries. (4) In the stomodseal region of polyps about as 

 many subsidiary couples of mesenteries as there are principal couples. (5) In the same 

 region of polyp entoccelic pleats thick, usually unconstricted at their bases, undivided, 

 extending over the greater part of width of principal mesenteries, broader and thicker in 

 outer half of width ; mesenterial mesoglsea comparatively thick, usually stouter in its 

 outer half. (6) Mesenterial endoderm vacuolated, considerably swollen, of more or less 

 uniform thickness along entire width of mesenteries. (7) Convolutions of mesenteries 

 abundant from stomodaeum to base of polyp massed in inter-mesenteric chambers, 

 almost blocking the whole gastro-vascular cavity. 



Remarks. A. Polyps. These are circular or oval in shape and small in size. Four 

 have each 7 principal couples of mesenteries, of which 3 are incomplete ; a smaller polyp 

 has only 5 principal couples ; about 10 subsidiary couples are present, 3 or 4 of which 

 do not extend below the stomodseum. The tentacles are short, present over all the 

 exocoeles but only over the principal entocoeles, the latter larger than the former ; every 

 tentacle has a swollen terminal battery containing a fair number of nematocysts II h 



