40 PERCY SLADEN TRUST EXPEDITION 



extending over more than the outer two-thirds of width of primary mesenteries, best seen 

 in second quarter from skeletal attachment ; mesoglsea much thicker than in non-pleatal 

 region. (4) In outer two-thirds of width of primary mesenteries (in stomodseal region of 

 polyp) endoderm consisting of large goblet-shaped vacuoles massed together, in inner one- 

 third a non-saccular layer. (5) Endoderm over stomodseum thin. (6) Filaments absent 

 from secondary mesenteries. 



Remarks. A. Polyps. The terminal batteries cover the greater part of the 

 exocoelic tentacles, but they are small and restricted to the ends of the entocoelic 

 tentacles ; the nematocysts in these are practically all of type I, each with from twenty- 

 five to thirty turns of the spiral ; owing to the comparative fewness the nematocysts' 

 terminal batteries not swollen. Ectodermal muscle-fibres with a longitudinal disposition 

 are visible in entocoelic tentacles. The stomodseal ridges are thicker than broad. The 

 convolutions of the mesenteries are massed together in the inter-mesenteric chambers and 

 extending down to the base of the polyps. Brown sacs suggesting mucous contents are 

 numerous in the coils of the mesenterial filaments, appearing above as clusters of round 

 vacuoles, lower becoming oval and arranged around a common protoplasmic mass con- 

 taining nuclei at its outer margin ; each has a deeper stained spot in its bluntly-pointed 

 inner end (PI. 1, fig. 7). Only nematocysts II are found in the filaments. The endoderm 

 is stained brown in hsematoxylin and eosin except at the base of polyps, thickened and 

 lobulated in the entocoelic tentacles owing to the presence of large vacuoles ; it is thin in 

 the entocoelic tentacles and in the non-pleatal region of the primary mesenteries ; below 

 the enterostome the mesenterial endoderm is a thin layer on either side of the mesoglsea ; 

 in the upper two-thirds of the secondary mesenteries there are endodermal vacuoles as in 

 the primaries. A circular layer of endodermal muscle-fibres is distinctly seen in the oral- 

 disc. Gonads were observed only in the primary mesenteries. In a male polyp each 

 directive mesentery had a single large testis consisting of a mass of mesoglsea with develop- 

 ing spermatozoa embedded (PI. 1, fig. 9), in the other primaries the testes were smaller. 

 They were also met with in the longitudinal sections of another polyp. In a female polyp, 

 taken from the same colony, ripe ova were found in three of the mesenteries in 

 single rows. 



Polyps examined, seven, all from a colony from Hulule, Maldives. 



B. Corallum. In the Copenhagen Museum there are seven of Forskal's originals of 

 Madrepora serailia from Kode Hav. Of these six (the largest measuring 16x12 '5 1x2 cm.) 

 constitute one species for which I retain Forskal's specific name, my type specimens 

 agreeing with them in every respect ; many of the corallites have the six primaries thicker 

 than the six secondaries and twelve prominent costse, those of the former being somewhat 

 more conspicuous than those of the latter (PI. 11, figs. 4 -—9). 



Of the two specimens in the Paris Museum from the Ked Sea referred by Milne 

 Edwards and Haime to Cyphastrea bottai, the larger (24 x 23 x 19 cm.) comes nearest the 

 present species but the calices are somewhat larger, up to 3 mm., average about 2-5 mm. ; 

 the specimen itself is somewhat rubbed, especially the corallites on its upper part. 

 Solenastrea sarcinula is represented by the very small figured specimen (4-5 x 3 cm.), its 

 only difference from C. serailia consisting in the higher projection of the corallites, about 



