Mr. E. W. H. Holdsworth on Caryophyllia clavus. 145 



On the Occurrence of Caryophyllia clavus on the 

 Coasts of Britain, with some Remarks on the Circum- 

 stances AFFECTING THE DISTRIBUTION OF CORALS AROUND 



the British Islands. By E. W. H. Holdsworth, F.L.S., 

 F.Z.S., ETC. 



By the kindness of the Rev. Thomas Hincks of Leeds, I have re- 

 cently been enabled to examine some specimens of coral which had 

 been forwarded to him from Shetland, and from Loch Fyne on the east 

 coast of Scotland. They prove to be new to Britain, and are iden- 

 tical with the Caryophyllia clavus of the Mediterranean, first described 

 as a fossil by Scacchi in 1833, and figured and described from recent 

 specimens under the name of Cyathina turbinata by Philippi in his 

 ' Catalogue of Sicilian Mollusca,' published in 1836. Several ex- 

 amples of this coral have been obtained from deep water in the above- 

 mentioned localities ; and an examination of characteristic specimens 

 of different ages has enabled me also to identify with this species two 

 small and much-worn corals which, in June 1857, were dredged 

 from a depth of 60 fathoms, about forty miles west of Scilly, by 

 Mr. S. P. Woodward of the British Museum, and kindly placed in 

 my hands a short time ago by that gentleman. 



This species of Caryophyllia may be readily distinguished from its 

 near ally, our common C. Smithii, by its conical form and finely 

 pointed base, as well as by the thinness of its walls and lamellae. 

 The general character of the polype, as described by Philippi*, agrees 

 with that of C. Smithii ; the integuments, however, are said to be 

 excessively delicate and transparent, so that the borders of the 

 lamellae can be seen through them. The body is of an orange-colour, 

 and the capitate tentacles whitish with metallic-green reflections. 

 The coral is frequently attached to a tube of Ditrupa, or the shell of 

 some deep-water univalve, or, in some cases, is entirely free. In 

 the British Museum are several specimens of this coral which were 

 brought from Sicily. These are all attached to a species of Turri- 

 tella. The occurrence of this second species of Caryophyllia in 

 three distinct localities on our coasts entitles it to a place among our 

 British corals ; and further investigation will probably show it to be 

 generally distributed in the deep water along our western shores. 



It may not be uninteresting to inquire here into the distribution 

 of corals around the British Islands, and to trace, as far as possible, 

 the cause of their frequenting only particular lines of coast. 



The existence of the coral-polype in our seas is mainly dependent 

 on the warmth and purity of the water. A tolerably high tempera- 

 ture is undoubtedly one of" the most necessary conditions for the well- 

 being of the delicate polypes whose calcareous lamellated skeletons 

 constitute the true stony corals. Only within the Tropics do we meet 

 with those vast reefs and extensive accumulations of coral-growth 

 which form so characteristic a feature of the seas in those warm lati- 

 tudes. The surface-water there becomes heated by the direct influ- 



* Arch, fur Naturgesch. t. i. p. 42, 1842. 



