The following are species with the fourth cycle incomplete : —
Caryophyllia cylindracea* , Reuss, sp. Wiltshire, Kent, Norfolk, Chalk, upper beds usually.
Nehon (Manche).
Bilin and Weiss Kerchlitz.
„ Lonsdalei, Duncan Dunstable.
The progress of research, especially in the investigations concerning the fauna of the deep sea, has shown that there are some remarkable exceptions to this rather hasty generalization.
Pourtales described Caryophyllia formosa, Pourt., in the ' Contributions to the Fauna of the Gulf-stream at Great Depths,' No. 6 (Bull, of the Museum of Comp. Zoology, Cambridge, U.S. 1868). This form was dredged up off Havana in 270 fathoms. It has four complete cycles in six systems. Although I have not seen the specimen, still I can but recognize, from the very able description, the decided fossil facies, if such a term may be tolerated, of the species.
During the last expedition of If .M.S. ' Porcupine '†, under the direction of Dr. Carpenter, P.R.S., and Mr. J. Gwyn Jeffreys, F.R.S., many specimens of Caryophyllioe belonging to several species were dredged up, some of which presented the perfect and others the imperfect development of the fourth cycle. Some species to which they could be referred had hitherto been recognized as extinct forms ; and others were new to science. Thus Caryophyllia arcuata, Ed. & H., a well-known Pliocene form, was found not to be an uncommon inhabitant of the deep sea; and Caryophyllia abyssorum, Duncan, a new species, was discovered in a dredging from the depth of 1095 fathoms off the coast of Portugal.
The falsity of the generalization which would restrict the Caryophyllioe with four cycles to extinct forms having been proved, it became necessary to compare the forms dredged up from great depths, and which had only four complete or incomplete cycles of septa, with the fossil forms possessing similar arrangements.
I was especially led to do this on account of my having detected some instances of remarkable persistence of form during some late examinations of large series of corals from different formations.
Whilst I was impressed with the great variability of the reef- building species of corals, and had obtained proofs of their increase of variation under alterations in the surrounding physical conditions, I became aware of the very persistent character and less variable nature of the corals of the deep-sea fauna.
During the examination of the corals dredged up from the Channel slope in 690 fathoms (No. 9 dredging, see Messrs. Carpen-
- Duchassaing (Anim. Rad. des Antilles, p. 15) described a species with an
irregular septal arrangement, but which is associated by MM. Milne-Edwards and Jules Haime with the Caryophyllioe having the incomplete fourth cycle ; but an examination of the plate (Hist. Nat. des Corall. plate D 1, fig. 1) proves that there are four complete cycles and part of a fifth, or else that the specimen is a monstrous form having seven systems. For a corresponding monstrosity see P. M. Duncan, Ann. & Mag. Nat. Hist. 1865, vol. xv. p. 276, pl. xi. fig. 2, e.
† My description of the stony corals dredged up in the expedition of H.M.S. ' Porcupine ' is about to be published by the Zoological Society.
