222 MR. S. O. RIDLEY ON THE CORALHID^. [Feb. 7, 



C secundum is no doubt in America, in company with the other 

 specimens obtained at the same time by the United-States Exploring 

 Expedition. The Red Coral (C7. nobile) occurs in the Mediterranean, 

 and among the islands (e. g. Cape-Yerd Islands, see Wyville 

 Thomson, Voy. ' Challenger,' Atlantic, i. p. 76) lying off the N.W. 

 coast of Africa ; it occurs nowhere^ else, so far as I have been able 

 to discover, G. secundum is recorded with doubt as from the Sand- 

 wich Islands ; it was probably obtained in the Pacific Ocean at any 

 rate ; O.johnsoni was obtained from Madeira. In the present paper 

 is described a fourth species, and one which is probably not new, 

 belonging to this remarkable and beautiful family : the one was 

 obtained from the island of Mauritius, and is now in the collection 

 at the British Museum ; the other is stated to come from Japan, and 

 will shortly be incorporated with the same collection. 



Arrangement of the Family. — The only attempt which has been 

 made at classifying the species is that of Dr. Gray in a Note read 

 before this Society, and published in its 'Proceedings' for 1867 

 (p. 125), and somewhat amplified in 'Catalogue of Lithophytes or 

 Stony Corals' (1870), p. 22, Dr. Gray divided the family and the 

 original single genus CoralUum into 3 genera, based mainly ou the 

 distribution of the "polypes" (meaning polype-cells, verrucse of 

 Verrill) on the branches, viz. : — 



(1) CoralUum, with the verrucas slightly elevated from the cortex 

 and scattered on all sides of the branches (inch C. nobile). 



(2) Pleurocorallium, branching in a single plane ; the verrucas 

 shghtly raised, confined to one surface, and mostly placed on small 

 branches chiefly found near the edges of the main branches (incl. 

 C. secundum, Dana). 



(3) Hemicorallium. The verrucee prominent, all occurring on one 

 side of the branches (incl. C.johnsoni, G-ray). 



With regard to this arrangment, it seems well to point out that 

 the characters on which it is founded appeal entirely to the naked 

 eye. In the allied members of the same group, the Alcyonaria, 

 Prof. KoUiker (see ' Icones Histiologicse') and Verrill (see various 

 papers in the Proc. Essex Institute, Trans. Connecticut Academy, 

 American Journal of Science, &c.) have shown good reasons for 

 the belief that the majority of those characters, such as colour, 

 manner of branching, presence or absence of anastomosis between 

 branches, to which alone those writers can appeal who do not 

 make use of a microscope in their researches, must be regarded 

 as usually of no more than secondary importance in the estimation 

 of the mutual affinities of the different subdivisions and species of this 

 group. From personal study I can testify to the truth of this principle 

 in the case of the MelitkceidcB, which are probably the nearest allies 

 of this family. In them anastomosis of branches may be simply a 

 varietal circumstance ; coloration of the internal parts is open to the 

 same remark, and external coloration is far more frequently so ; the 

 manner of branching is much the same in all ; so that, for classifi- 



' It is found fossil in the Upper Pliocene and Quaternary deposits of South 

 Italy, cf. Seguenza, Atti Ac. Line. (3) Mem. sc. fis. mat. nat. iii. pp. 331, 373. 



