1/4 THE OCEAN WORLD. 



four. The cells between the chambers are sometimes open in all 

 their depth, sometimes more or less shut up by transverse plates ; 

 these, being independent of each other, are never reunited in the 

 breadth of the visceral cavity, so that they constitute discoid plates 

 such as we find in the tabular and rugose Madrepores. The animals 

 belonging to this group, which may be characterised as stelliform or 

 star-like, are very abundant in every sea, and in several geological 

 formations. They constitute many genera, among which may be 

 noted the Millcporina of Ehrenberg, the polypidom of which Dr. 

 Johnston describes as " calcareous, fixed, plant-like, branching or 

 iobed, with cells scattered over the whole surface, distinct, sunk in 

 little fosses, obscurely stellate, the lamellae narrow and almost 

 obsolete."* In Turbinolia, the animal is simple, conical, striped, 

 furrowed externally with larger and smaller ribs, the mouth sur- 

 rounded by numerous tentacula, and solidified by a calcareous 

 polypidom, which is free, conical, and also furrowed externally ; 

 attenuated at the base, but enlarged at the summit, and termina- 

 ting in a shallow radiated lamellar cup or cell. Several specimens of 

 T. milletiaiia have been dredged off the coast of Cornwall, and the 

 west coasts of Scotland and Ireland. 



T. miUdiaiia is described as being coral-white, wedge-shaped, some- 

 what compressed, with interspaces or ribs equidistant, smooth, and 

 glossy. Above, the ribs turn over the edge, and are continued into the 

 centre of the enlarged cup, forming its lamellae. " That the zoophyte 

 must have lived for some time after having become a movable thing, is 

 proved," says Dr. Johnston, " by the ribs being continued beyond or 

 round the point of attachment." The specimen here described was 

 dredged alive ; and Prof. Forbes says of it that " it is a most interest- 

 ing and beautiful species, the more so as it is certainly identical with 

 Defrance's Turbinolia millctiana, found in both the crag formations." 



In the sub-family of the Zoanthidse, the polypes occur in clusters, 

 and are multipled by buds, rising from a common creeping, root-like, 

 fleshy base ; they thus present a sort of coriaceous polypidom, as in 

 Zoanthus (Fig. 59). In the British Channel the species which Dr. 

 Johnston has named Z. Couchii, after Mr. Couch, jun., is found along 

 the Cornish coast, on flat slates and rocks, in deep water, and from 

 one to ten leagues from the shore. It is very small, resembling 

 both in shape and size a split pea. When living, its surface is plain 

 but glandular, becoming corrugated when preserved. AVhen semi- 

 expanded, which is its favourite state, it elevates itself to twice its 



* Johnston's "Zooptiytes," vol. i. , p. 194. 



