364 Royal Society. 



been separated, and had they been assumed to have come from 

 different localities, new species would have been made of them. 



Several specimens are very costulate, and there are crests to 

 all the larger costae ; in some there are wart-like growths in those 

 situations, and in these forms the calice is sometimes widely open, 

 or very compressed, or normally slightly so at its orifice. 



In at least one fourth of the specimens the shape of the corallum, 

 instead of being subturbinate and compressed above the round 

 pedicel, is tall and cylindrical ; and there are no costal ridges of 

 any importance. Moreover the size of the calices and septa varies 

 in this series. 



Some specimens, otherwise normal, have very broad basal ex- 

 pansions out of all proportion with the height. But the most 

 interesting variation is noticed in those specimens which have 

 widely open calices and exsert septa ; for, added to these specific 

 structures, are costal crests, ridges, processes, and root-like projec- 

 tions coming from the body, peduncle, and base. These projections 

 are either free at their end or are attached to some support; some- 

 times the growths are in relation to the costal line, and in others they 

 cannot be maintained to be so, and they are either smooth, granular, 

 or like shagreen. There is no epitheca on the coral, and the root- 

 like projections are therefore growths of the ectoderm. Some act 

 as supports ; but most have been produced by the irritation of an 

 AnneUd, which, after boring out of the cable, came in contact with 

 the coral, which endeavoured more or less successfully to cover 

 it up. 



Those processes which are bej'^ond the reach of Annelids and 

 which act as supports singularly resemble those root-like growths 

 which are of generic or specific importance in many groups of 

 Madreporaria. 



Flahellum, RTiizotroclms, RMzophyUum, Omphynui, &c. are genera 

 which possess such root-forming species. But the root-like processes 

 oiFlahellum, have a higher physiological interest than those of Desmo- 

 plujUum ; for some finally separate the base of the coral from its 

 attachment by their do-miward growth-pressure ; nevertheless the 

 development of root-processes by the cable-covering Desmophylla is 

 suggestive and important, although some are morbid growths. 



The cylindroid specimens would most probably be considered 

 specifically distinct from the others were they found away from 

 them or in strata. The}'^ are very suggestive ; for in palaeontology 

 the shape of the corallum, the contour of the calice, and the relative 

 size of the septa are often considered to establish species ; and such 

 genera as Trochocyathus, Trocliosmilia, and Monilivaltia amongst 

 Mesozoic corals, and Cyatliophyllia and Zaphrentis amongst the 

 Eugosa, teem with specific names which are not established on 

 better grounds than that of the cylindroid Desmophyllum. 



The Lophohelice on the cable present great bud variation ; and 

 the young and -old corallites are of many different shapes, from the 

 turbinate to the tubular. But the most important structural peculi- 



