100 PERCY SLADEN TRUST EXPEDITION 



12 — 17 meeting columella, each witli a blunt paliform lobe and 3 or 4 blunt teeth above 

 it, usually perforated behind paliform lobes. Subsidiary septa alternating with the 

 principals, the broader ones curving towards and fusing with sides of principals. Exsert 

 ends of septa arched, serrate. Costse with transversely extending granulations, usually 

 meeting in inter-corallite furrows, tending to be united by transverse ridges where they 

 meet. Columella well developed, trabecular, about ^ width of calyx. 



Multiplication by equal or sub-equal fission. ' 



The corallites towards the edges project up to 3 '5 mm. and increase in diameter from 

 calicular margins (6 or 7 mm.) to bases (9 mm.). They are wider apart, up to 6 mm., 

 with calices shallower, septa sloping, thicker and rougher, and with usually an alternating 

 cycle of smaller costse, hardly represented by septa within. 



The skeletal facies of this species has a general resemblance to that of Echinopora 

 gemmacea. 



Polyps, (l) Both entocoelic and exocoelic tentacles present. (2) Stomodseal ridges 

 narrow, thicker than broad, as in Favia Jiululensis, inner surface slightly convex or flat. 

 (3) About nine principal couples of mesenteries. (4) In the stomodeeal region of polyp 

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

 the stomodeeal region of polyp, entocoelic pleats thick, undivided, slightly constricted at 

 their bases, narrow on outer half of pleatal region, directed obliquely towards the stomo- 

 dseum and extending over outer halves of principal mesenteries ; pleatal region of mesoglaea 

 thicker than non-pleatal region, inner half of former stouter than its outer half and with 

 broader pleats. (6) Mesenterial endoderm thicker in pleatal region. (7) Convolutions 

 of mesenteries not abundant, but extending to base of polyp. 



Remarks. A. Polyps. The polyps of this species were not in a good condition for 

 detailed study. 9 principal couples of mesenteries were present in each of 3 polyps, 7 and 

 8 couples in two others ; of these, 1 to 5 couples were incomplete ; subsidiary couples 

 numbered 8 to 10. The tentacles were short, with well-developed terminal batteries 

 of the usual structure and with not more than 4 or 5 sub-terminal ones. The stomodgeum 

 is oval in transverse section, its diameters in the retracted condition being TS and 1 mm. ; 

 owing to the radial contraction of the mesenteries some of the ridges appear concave 

 In transverse section ; the mesoglsea is not thickened in the ridges. The endoderm in the 

 tentacles and stomodaeal wall is quite thin. Gonads were not present in any of the polyps. 



Number of polyps examined, five, 3 from one colony and 2 from a second, both 

 from Dongonab, Red Sea. 



B. Corallum. Klunzinger's type of Orhicella laxa is a small specimen measuring 

 10x9x4 cm. In the Hofmuseum, Vienna, are three specimens of the " Pola " expedition, 

 referred by Marenzeller to Orhicella laxa, Klunz. Two of these are large examples, 

 one from Sherm Abban (No. 15916) measuring 19x19x15 cm., the other from Koseir 

 (No. 2276) measuring 30 x 16 x 8 cm. 



Locality. Red Sea (5). Not recorded from elsewhere. 



10. Favia hirsvta (Milne Edwards and Haime). (PL 24, figs. 7 and 8.) 

 1816. Astrcea dipsacea, Lamarck, Hist. Anim. sans vert., ii, p. 262. 



