104 PERCY SLADEN TRUST EXPEDITION 



Corallum, Incrusting. Peritheca compact. Corallites circular, unless dividing 

 when elongated, projecting up to 1"5 mm., usually to "75 or I mm., up to I'o mm. apart, 

 usually closer but separated by inter-callcinal grooves. Calices 3 — 4 mm. in diameter, 

 1 — 2 mm. in depth. 



Septa comparatively thin, vertical (edges somewhat concave in the shallower calices), 

 with denticulate edges, spinulose sides, exsert to '5 — 75 mm., 16 — 25 in number; 

 12 — 18 septa meeting columella, most of these with rough blunt paliform lobes (usually 

 a ring of 12), which in shallower calices reach to the calicular margins ; subsidiary septa 

 often curving towards and fusing with sides of principals. Exsert ends of septa arched, 

 denticulate. Generally a cycle of very narrow septa alternating with the principals and 

 subsidiaries, with or without corresponding costee. Costse conspicuous with transversely 

 extending granulations, stopping at inter- corallite grooves or meeting those of adjacent 

 corallites in notches. Columella spongy or dense, ^ — ^ width of calyx. 



Multiplication by budding (small corallites intercalated between larger ones) and 

 by fission. 



The polyps were all badly preserved. Though budding undoubtedly takes place 

 among them, neither of the polyps sectioned from a specimen from Rotuma had any 

 directive couples of mesenteries ; one of them had 6 principal couples of mesenteries and 

 19 subsidiary couples. In its stomodeeal region the entocoelic pleats were narrow and did 

 not extend beyond the outer one-third of each principal mesentery. Tentacles were 

 present over all the entocoeles and exocoeles. 



Remarks. Corallum. In the Paris Museum is a small incrusting specimen 

 (6 '5 X 6 cm.) from Australia, Milne Edwards and Haime's HeliastrcBa annuligera (PI. 37, 

 fig. 3), with which Gardiner's figured examples of Orbicella annuligera are identical. Two 

 other specimens are named by them Plesiastrcea versipora, Ed. and H., one from Indian 

 Ocean measuring 10x5 x3'5 cm. (PL 23, fig. 3), the other smaller from an unknown 

 locality ; in the latter and on one side of the former the corallites are closer and with 

 polygonal inter-corallite furrows. Plesiastrcea quatrefagesana, Ed. and H., is represented 

 by a small specimen with rudimentary paliform lobes from an unknown locality. In all 

 these specimens multiplication is mainly by budding. Milne Edwards and Haime's types 

 of HeliastrcBa laperouseana are two small incrusting specimens from Vanikoro, which 

 perhaps belong here (PL 25, fig. 9). 



A badly-cleaned fragment in the " Challenger " collection, with five or six corallites 

 from Bermuda, referred by Quelch to Astrcea coarctata (Duchassaing and Michelotti), 

 comes nearest the present species. 



Localities. Maldives, Goidu (2). Minikoi (3). Seychelles (3). Chagos, Salomon 

 (9). Rotuma (l). Also from Australia and Vanikoro (Milne Edwards and Haime) ; 

 ? Bermuda (Quelch). 



13. Favia wakayana (Gardiner). (PL 25, fig. 4.) 



1899. Orbicella wakayana, Gardiner, Proc. Zool. Soc. London, p. 753, pi. 49, lig. 2. 



1899. Orbicella versipora, Gardiner, Proc. Zool. Soc. London, p. 753 (non Plesiastrcea versipora, Milne Edwards 

 and Haime). 



