FAMILIES AND GENERA OF THE MADEEPORAEIA. 11 



The genus DesmopTiyllum was established by Ehrenberg, Corall. 

 des Eoth. Meer. p. 76 (1834). It contains many recent and fossil 

 species, and is eminently Smilotrochoid. There is great varia- 

 tion in the shape of individuals of some of the species, and ab- 

 normal growths are produced around the base and from the wall 

 by the irritation of parasites and any instability of the surface of 

 attachment. The forms may grow to a considerable size, may 

 adhere by their sides and form groups, and the same species will 

 present short, long, broad-based, narrow-based, large and small 

 caliced, costulate or non-costulate individuals. 



In some instances the base extends as a film of hard matter on 

 the supporting body, and in others there are rootlets. 



The majority of species have no epitheca ; but a recent form 

 which cannot be separated from the genus has it. Moseley 

 notices that his great Desmopliyllum ingens is covered with an 

 abundant dense epitheca*; and some forms of Desmophyllmn 

 crista galli, Ehr., sp.f, have it and others have not. But the 

 epitheca is not separable from the wall. 



Ehrenberg's definition, as given by MM. Milne-Edwards and 

 Jules Haime %, is too contracted in some parts, and not suffi- 

 ciently elaborate in others. As amended the genus may stand as 

 follows : — 



Grenus Desmophtlltjm, Ehr. 1834, amended. 



The corallum is fixed by a large or small base ; the body may 

 be long or short, straight, or slightly curved and twisted, with 

 or without " rootlets " springing from the wall. Calice widely 

 open, fossa deep ; axial space vacant. Septa numerous, exsert, 

 unequal in height, often overhanging the margin. Costse visible 

 near the calice, irregular, often as crests, nodules, or ridges here 

 and there on the wall. Epitheca may or may not exist. Surface 

 usually smooth or granular. 



Distribution. — Hecent. Atlantic and Pacific Oceans, Australia, 

 Western Patagonian seas, and Mediterranean. — Fossil. Upper 

 Tertiary strata of Europe, 



Subgenus Jayania, Duncan^ Proc. Zool. Soc. Land. 1876, 

 p. 434. 



The base is broad, the calice compressed, the larger septa are 



* Moseley, * Challenger ' Eeport, p. 61. 



t Duncan, Proc. Eoyal Society, p. 133 (1877). 



\ Hist, Nat. des Corall. vol. ii. p. 76. 



