20 



Those of the third cycle unite with those of the second just where the paliform 

 processes of the latter arise. Those of the other cycles are low sharp slightly 

 crenulate ridges, which gradually eud low down in the fossa. 



The corallum is white with a brownish tinge externally. 

 Off Pedro Bank (Laccadive Sea), 636 fms. 



Subfamily Ttirbinolina:, Edw. & H. 



vii. DESMOPHYLLTJM, Ehrenberg, Edw. & H. 



13. Desmophyllum vitrewm, n. sp. PI. ii. figs. 2, 2-6. 



Encrusting dead corals in colony-like masses. 



The corallum is snow-white with a glistening external surface. From an 

 encrusting base a stout cylindrical slightly-curved stalk of varying length arises 

 and rather suddenly expands into a turbinate calyx, with a spreading lip, the 

 outline of which varies from circular to narrowly-elliptical. Sharpish costae, 

 corresponding with the first three cycles of septa, are present on the calicular 

 wall only, not on the stalk : the surface between them is generally rippled. 



The septa, like the thecal wall, are of a compact porcelain-like texture, 

 and their surfaces are finely and sharply granular. They are in six systems 

 and four complete cycles. Those of the first two cycles are about equal in size, 

 and are large and strongly exsert : they simply meet together and fuse at the 

 bottom of the cup, with hardly any " callus," and sometimes they do not meet 

 at all. Those of the third cycle are a good deal larger and more exsert than 

 those of the fourth : they never fuse with their predecessors, and often descend 

 below the point where the latter fuse. Those of the fourth cycle are small and 

 little exsert, but they descend deep into the cup. 



Though the large septa of the first two cycles are described as about equal, 

 no two are of quite the same size, and, in an unbroken specimen, one of them 

 may be found jutting up far above the other eleven. 



It is useless to give measurements of such a variable form ; an average 

 specimen, picked out at random, is 35 millim. high and has a circular calyx 

 27 millim. in diameter. 



Hundreds of specimens were dredged, along with the Caryophyllia para- 

 doxus before described, off the Travancore coast, at 430 fms. 



This species appeared to me to be as closely as possible related to D. eburneum 

 Moseley, dredged by the " Challenger " off Patagonia at 34*5 fms. ; but 

 Mr. Jeffrey Bell, who has very kindly compared specimens, says " I cannot 



think that your Desmophyllum is the same as D. eberneum but I am not 



quite sure that it is not D. ing ens" 



