184 E. p. TOiEES ON ilADEEPOEAEIA 



from Combe Down, I am convinced tliat tlie supposed colnmella 

 does not exist in anj of them, and that, as I shall presently show, 

 they are identical with the Isastrcea Conyheari of the same authors, 

 fi'om the same locality. In fact the supposed columella is nothing 

 more than the blending together of the inner margins of the septa, 

 which takes place in a very uncertain manner quite low down in 

 the corallites, and becomes visible only when the corallum is much 

 worn down. It was from such a worn specimen that the figure of 

 WSL. Milne-Edwards and Haime was taken. With the full conviction 

 therefore that the Coombe-Down coral cannot consistently be placed 

 either in Clausastrcea or FUrastrcea, I have created a genus for its 

 reception which I define as follows : — 



The corallum is massive and more or less globular. The calices 

 are large and shallow ; there is no wall surrounding the corallites, and 

 the septa of one calice meet and unite with those of the adjoining 

 ones. They are not numerous, and are strongly denticulated. 

 There is no columella. The dissepiments are very numerous, com- 

 pletely filling up the loculi. They are well developed and strongly 

 arched. 



Plataste^a Co>^teeaei, M.-Edw. and Haime, sp. 



Isastrcea Conyheari, M.-Edw. and Haime, Brit. Poss. Cor. pi. ii. 

 p. 113, pi. xxii. fig. 4 (1851). 



Olausastrcea Pratti, M.-Edw. and Haime, Brit. Eos. Cor. pi. ii. 

 p. 117, pi. xxii. fig. 5 (1851). 



All the specimens recently collected at Combe Down may be re- 

 ferred either to Clau^astrcea Pratti or to Isastrcea Conyheari, according 

 to the condition of the specimen examined. In its normal form 

 this species is more or less globose, and in such specimens, when 

 not too much worn, the calices have much the form and appearance 

 of those of Isastrcea Conyheari, But frequently the corallum has 

 departed from this regularity of outline, and the departure has been 

 accompanied by a corresponding irregularity in the form of the 

 calices, and in the degree of development of the septa where they 

 meet in the fossula. Such specimens, if much worn, present all the 

 appearance of Clausastrcea Pratti ; and indeed the characteristics of 

 both the supposed species may sometimes be observed on different 

 parts of the same coraUum. 



OoxiocoEA, sp. 



I have met with a single specimen referable to this genus, which 

 in size, mode of growth, and so far as can be seen in its calicular 

 characters, bears some resemblance to Goniocora socialis. It is too 

 much overgrown with Bryozoa to permit examination of the mural 

 costse, and the septa are only visible when the ends of the coraUites 

 are broken off. It has very thick walls, and thin and straight septa. 

 The first cycle of septa extends almost to the centre of the calice, 

 the secondary ones are three fourths the length of the primaries, 

 and the tertiary septa are rudimentary. 



The specimen here mentioned was obtained by me at Parley 



