202 CEYLON PEARL OYSTER REPORT. 



Cycloseris tenuis, Dana. 



Fungia tenuis, Dana, ' Zoophytes,' p. 290, 1846. 



Cycloseris sinensis, M. Edw. and H., 'Ann. des Sci. Nat.,' 3 e ser., xv., p. 112, 1851. 



Cycloseris hexagonalis, M. Edwards and Haime, loc. cil. 



Cycloseris hexagonalis, Gardiner, Willey's 'Zool. Results. Solitary Corals,' 1899. 



Professor Herdman's collection contains seven specimens, of which the largest 

 measures 40 millims. in diameter, while the smaller specimens vary from 22 millims. 

 to 9 millims. in diameter. The smaller individuals, among which are two somewhat 

 hexagonal forms, agree in all respects with the definition of C. hexagonalis, M. Edw. 

 and H, and, allowing for individual variation, with Gardiner's excellent photographs 

 of this species (20, plate xx.). Two of them have definite basal scars, not yet filled 

 up by secondary deposit, and the costse reach to the edges of the scars ; in the other 

 specimens the costse, and the extent of the central basal granulation, differ to a 

 considerable extent, but the septal characters are quite uniform and none of the 

 septa are fenestrated. In the largest specimen the two last cycles of septa are 

 fenestrated, a character which would attach it to C. sinensis, M. Edw. and H. This 

 species however is synonymous with Cycloseris [Fungia) tenuis, Dana, and the latter 

 name has the priority. Except for the fenestration of the lower cycles of septa there 

 is absolutely no difference between the largest and the smaller specimens in Professor 

 Herdman's collection, hence I am of opinion that hexagonalis and sinensis are merely 

 varieties of Dana's species tenuis, and must be absorbed into it. 



Diaseris, M. Edwards and Haime (37). 



Quelch (45, p. 121) has expressed his opinion that the specimens referred to this 

 genus are nothing more than broken and distorted individuals of Cycloseris tenuis, 

 but I cannot agree with him. Professor Herdman's collection contains a specimen of 

 C cyclolites, which has been broken and repaired, and shows considerable distortion 

 and re-arrangement of the septa, but its characters are widely different from Diaseris. 

 It is true that the structure of the wall, the septa, and even of the rudimentary 

 columella of Diaseris are very similar indeed to that of Cycloseris, as M. Edwards 

 and Haime pointed out, but the former genus is sufficiently distinguished by its 

 peculiar method of reproduction by radial division, whence the corallum has the 

 appearance of being composed of a number of lobes with rounded edges, or is divided 

 into wedge-shaped fragments. This method of reproduction has been so sufficiently 

 and clearly described by SfiMrER (49) that I can add nothing to his account, which is 

 fully borne out by a study of the Ceylon specimens. 



Diaseris distorta, Michelin. 



Fungia distorta, Michelin, ' Mag. de Zool. V. Zooph.,' pi. 5, 1843. 

 Diaseris distorta, ' Ann. des Sci. Nat.,' 3 e se>., xv., p. 118, 1851. 



Numerous specimens and cuneiform fragments from off Mutwal Island, and some 

 small fragments and specimens from deep water off Galle and from Kaltura. 



