with, fetid mud. The branching, bush -shaped and dendroid forms are usually found upon a rocky bottom; and the simple corals generally select a shelly foundation or a foraminiferous ooze.
The genus whose species are dwellers in the deep sea, and which is most familiar to European naturalists, is Caryophyllia. It is a genus whose species are invariably simple in form or solitary; they reproduce by ova alone, and do not form a compound corallum by gemmation.
Alphonse Milne-Edwards[1] obtained numerous specimens of varieties of the Mediterranean Caryophyllia arcuata and Caryophyllia clavus from a depth of between 2000 and 2800 metres (1110 and 1550 fathoms) in the sea between Corsica and Algiers. Edward Forbes and others, since his time, have obtained Caryophyllia cyathus from a depth of from 5 to 200 fathoms. Caryophyllia borealis, Fleming, has been dredged up by Messrs. MacAndrew, Norman, and Gwyn Jeffreys in corresponding depths in the North Sea; Mr. Norman dredged up thousands in one spot in 70 fathoms; and therefore the species may be considered a common one over the coralliferous area of the western European seas.
The genus Balanophyllia has species in the Mediterranean at 80 fathoms; and Mr. Gwyn Jeffreys has found one at 340 fathoms, off the south-west of Ireland. Species of it are found in the deep seas off nearly every part of the world that has been mentioned as having a neighbouring deep-sea coral fauna.
Flabellum has a species (Flabellum anthophyllum) in the Mediterranean, in the Bay of Biscay, and in the North Sea; and others are found at considerable depths amongst the remote deep-sea faunas.
The Nullipore zone of the Mediterranean is inhabited by a species of Desmophyllum, which is found in deep water off Madeira and Cape Breton. Others have been found off Japan, and in the Pacific off the south-west coast of America.
There is a species of Paracyathus which is found at a depth of from 30 to 40 fathoms in the Shetland seas; and the genus is represented in the deep-sea fauna of the Mediterranean.
The genus Sphenotrochus has species in deep water off the Cornish coast, the west coast of Ireland, and near the Isle of Arran.
These are the typical deep-sea simple corals. None of them throw forth buds, and they all vary much in shape; the depth of water and the nature of the sea-bottom have much to do with the peculiarities of some forms.
The other deep-sea corals are compound Madreporaria. The great branching Lophohelia prolifera lives at a great depth in the North Sea, at more than 400 fathoms on rocky ground off the south-west coast of Ireland[2], and in deep water in the Mediterranean. This is a typical deep-sea form; and the absence of the cellular coenenchyma is, with one exception, a characteristic of the deep-sea compound corals, just as its presence is almost invariable in the species of the reef fauna. A huge branching coral, Dendrophyllia
