74 PERCY SLADEN TRUST EXPEDITION 



present but nematocysts rare. The calicoblast is thickened near skeletal attachments of 

 mesenteries, in transverse section resembling ectoderm of oral-disc. In some of the 

 terminal batteries numerous long narrow bodies, homogeneously stained pink in eosin, 

 are seen (as in Favia doreyensis, Ed. and H.) which may probably be immature stages in the 

 development of nematocysts II b. The mesoglsea is thick. The entocoelic pleats extend 

 over the outer halves of primary mesenteries in the stomodseal region of polyps, being 

 narrow, thick and unconstricted at their bases, below stomodaeum becoming broader and 

 extending over the greater part of the width of mesenteries, some of them being sub- 

 divided. Mesenterial mesoglcBa is stouter in pleatal region, thickening again towards 

 stomodaeum, the connecting sheet being narrow and thin. Groups of small bodies stained 

 dark in iron hsematoxylin are present in the outer mesenterial mesoglsea, probably spores 

 of algae. The endoderm of oral-disc is not thicker than the ectoderm over it and contains 

 numerous algse ; the mesenterial endoderm is thickened on either side of the inner stouter 

 region of mesoglaea. 



Polyps examined, three from a specimen from Minikoi. 



B. Corallum. In Lamarck's collection in the Paris Museuna are two small specimens 

 (8x8 X 3'5 cm. and 8"5 x 5"5 x 2"5 cm.) from " mers Australes " named Heliastrcea heliopora 

 by Milne Edwards and Haime which were doubtless Lamarck's originals of Astrea 

 heliopora (PI. 20, fig. 8). These are similar to Gardiner's examples of Orhicella mini- 

 Jcoiensis, but the calices are somewhat smaller with an average diameter of about 7 mm., 

 and a cycle of thin costae are present regularly alternating with the main ones, those 

 of neighbouring corallites usually meeting in notches, their corresponding septa being 

 quite rudimentary or absent. 



Resembling Lamarck's examples are two undescribed specimens in the Berlin 

 Museum, which Dr Weltner tells me were collected by Dr Dahl in 1897 from Ralum (New 

 Pommern). One of these is large measuring 30x21 cm., the other a hump, 12x11 cm. 

 in size ; the secondary septa in their corallites are much thinner than the primaries, 

 some of them not reaching the columella ; an alternating cycle of thin costae are present 

 and the columella is about one-third the width of the calices. 



Vaughan records a single specimen from French Somaliland, East Africa, which he 

 says is identical with Orhicella minikoiensis, Gard. 



Localities. Minikoi (4). Also from Australia (Lamarck), French Somaliland 

 (Vaughan), New Britain (Dahl). Not known from the Red Sea. 



ADDENDA. SOME TYPE SPECIMENS. 



The following species are not represented in my collections, but I have examined 

 examples. From a study of their septal an-angement there is hai'dly any doubt that they 

 possess both the bilateral and hexameral symmetries, but it is not possible to determine 

 tbe genera to which they belong without examining their polyps. 



1. Stephanoccenia intersepta (Esper); Ed. and H., Ann. Sci. Nat., 3^ ser., x., PL 7, fig. 1, 

 1 a and b, and Corall. ii., p. 265. 



In Milne Edwards and Haime's three examples of this species the corallites are small 



