SOLITARY CORALS. 193 



Cyathotrochus herdmani, n. sp. Plate L, figs. 2 and 2a. 



Height of corallum, 7 millims. ; longer axis of calice, 10 millims. ; shorter axis, 

 7 5 millims. The characters are those of the genus. The septa and the bluntly 

 pointed basal part of the corallum are white, the rest of the wall of a dull Indian-red 

 colour. The wall and costee are covered with close-set but very fine granules, which 

 can only be distinguished by the aid of a strong lens. A single specimen from the 

 west of Periya Paar. 



After some hesitation I have founded a new genus to receive this species, which 

 does not correspond exactly with any described genus of the Turbinolidse. It is 

 undoubtedly closely allied to Troehocyathus, from which it differs only in the form of 

 the pali, which should perhaps be described as paliform lobes rather than true pali, 

 us they are evidently the thickened inner continuations of the septa, separated from 

 the latter by a notch which, although fairly deep, does not extend to the bottom of 

 the septum. These pali, or paliform lobes, form a single crown, not two crowns as 

 in Troehocyathus, and they do not form chevrons as in Trojndocyathus. The 

 characteristic feature of the species is the keel-like projection of the costse at each 

 end of the long axis of the corallum, suggesting an affinity to Tropidocyathus 

 (Troehocyathus) lessoni. But in this latter species, as Michelins' (34) and 

 Alcock's (3) figures show very clearly, the corresponding costa? are very much 

 enlarged and form aliform expansions extending round the base of the corallum, 

 whereas in Cyathotrochus they are but slightly enlarged to form ridges extending 

 scarcely half way to the base. 



Heterocyathus, M. Edwards and Haime (35). 



Stephanoseris, M. Edwards and Haime (38). 



Heterocyathus aequicostatus, M. Edw. and H. 



Stephanoseris rousseaui, M. Edw. and H., 'Hist. Nat. des Cor.,' t. iii., p. 56, 1860. 



H. philippinensis, Semper, 'Zeit. Wiss. Zool.,' xxii., p. 254, 1872. 



H. parasiticus, Semper, loc. cit. 



H. pulchellus, Rehberg, ' Abh. Ver. Hamb.,' xii., p. 8, 1892. 



H. oblongatus, Rehberg, loc. cit. 



H. aequicostatus, J. C. Gardiner, 'Mar. Invest, in South Africa,' "Turbinolid Corals," 1904. 



Professor Herdman's collection contains numerous specimens of this interesting 

 species, of all sizes, and apparently collected from all the localities in which he dredged. 



Mr. Stanley Gardiner has recently shown how very variable this species is, 

 and has absorbed the various species of Semper and Eehberg. The Ceylonese 

 specimens also show great variety, and, though I have not as large a collection for 

 comparison as Mr. Gardiner, I have no doubt of the identity of these specimens 

 with //. aequicostatus, and further, I have no doubt that the forms first described by 



2 c 



