148 A. Alcock — Newly-recorded Corals from the Indian Seas. [No. 2, 



Several specimens dredged by Professor Wood-Mason in the Anda- 

 man Sea. In all the specimens, except two very young ones, the coral- 

 lum is tunnelled apparently by a worm, just as in Heterocyathns and 

 Heteropsammia, except that the aperture for the exit of the worm instead 

 of being on the base is at one side of the oral fossa. 



Before goiug on to describe a new species of the genus Diaseris, I 

 must here remark that our beautiful series of Diaseris freycineti, and of 

 the species about to be described do not support Mr. Quelch's opinion 

 that the species of Diaseris are merely the results of the fracture and 

 repair of Cycloseris. 



25. Diaseris fragilis, n. sp. PI. V, fig. 11. 



The corallum is flat and very thin. In its youngest stage the 

 corallum is almost circular with a triangular lobe breaking through an 

 arc of about 90° of its circumference and projecting to form a sector of 

 a much larger circle. 



This lobe appears with age to spread round the original disk until 

 this in turn becomes a small lobe occupying not much more than 50° of 

 the circumference of the grown coral. 



The full-grown coral forms an irregular ellipse divided into four 

 lobes in opposite pairs, one pair being large (each lobe with a margin 

 equal to about 180° of the entire circumference), and the other pair being 

 small (each lobe with a margin extending through about 55° of the entire 

 circumference). The lobes are very distinctly delimited up to the very 

 cfiitre of the corallum, which has the appearance of being composed of 

 four artificially cemented pieces. 



The costa? are in the form of very close delicate granular striations, 

 alternately unequal. 



The septa, which appear to be in eight cycles in six irregular sys- 

 tems, are thin with very finely and evenly serrate edges and granular 

 surfaces : they are usually low, but the primaries and secondaries are 

 unequally elevated near the fossa. 



The synapticulse near the centre are coarse, close and equidistant, 

 and form regularly concentric circles, as in Bathyactis, throughout the 

 interseptal chambers : near the margin they are much more delicate, 

 and are not equidistant. 



The fossa is conspicuous and a columella is usually absent, al- 

 though sometimes a few distant papillae are visible. 



The largest specimen measures 50 mm. in the major diameter and 

 41 mm. in the minor and is not more than 6'5 mm. in height to the tip 

 of the highest septum. 



Dredged in the Andaman Sea by Professor Wood-Mason. 



