1882. } MR. S. O. RIDLEY ON THE CORALLIID. 223 
cation, recourse has to be had mainly to the characters of the spicula 
and of the verruce. 
The want of good series of individuals of any known species of 
Coralliide except C. nobile is an obstacle to the full discussion of 
the natural relations of the different forms; a few facts only can be 
noted at present as bearing on the subject. Beginning with the 
comparatively common Corallium nobile, Pallas (rubrum, Costa) 
we find a cylindrical axis, usually branching seldom, but dicho- 
tomously and most commonly in an arborescent manner, which, 
though tending towards growth in one plane, yet almost invariably is 
actually in various planes ; the cortex quite conceals any inequalities 
of the surface ; and the verrucz! (or calicles) project dome-like from 
all sides of the branches. Variations are frequent, especially in mode 
of growth ; but these are by far the commonest characters of the 
species. The colour of the axis varies not uncommonly from crimson 
to pale red, rarely to yellow, and more rarely to white; the spicules 
are of one type, viz. a hexahedral oblong form, the angles being 
formed by broad truncate but microtuberculate tubercles, which 
preserve the chief features of their characteristic form throughout 
all varieties of the external form of the coral. (Cf Lacaze-Duthiers, 
Hist. Nat. Corail, p. 70—‘ toutefois en recherchant bien, on finit par 
découvrir une forme qui, résumant toutes les autres, peut étre regardée 
comme la type.’’) 
Corallium (Hemicorallium, Gray) johnsoni, P. Z.8. 1860, p. 393, 
Radiata, pl. xviii., differs in several particulars from the former 
species, besides the branching essentially in one plane, the strictly 
anterior position of the verruce, and their considerable protrusion 
from the surface, which are the chief points insisted on by Dr. Gray. 
Thus the cream-coloured cortex is about *5 mm. thick, about twice 
the thickness which it has in C. nobile ; on the terminal branches 
the calicles rise abruptly from the surface, are truncate above, and 
measure 1°5 to 2 mm. in average diameter. The spicules have not 
hitherto been described; and their characters, in the one case, are so 
remarkable, and have such an important bearing on the affinities of 
both the genus and family to which the species belongs, that I now 
proceed to describe them. 
Spicules of two kinds :—(i.) cylindrical, octoradiate, having a short 
stout shaft terminated at each end by a tubercle; two pairs of tubercles 
also project from each end of the shaft, in the same plane as the 
terminal ones, but at right angles to its long axis; on the anterior 
side (reckoning the two pairs of tubercles just mentioned as lateral) 
a tubercle projects at right angles to the long axis of the shaft, and 
also to the plane in which the lateral tubercles lie ; on the posterior 
side a similar tubercle is similarly placed, but at the opposite end of 
the spicule ; the ends of the short, broad, truncate tubercle are micro- 
tuberculate with few, sharp, smaller tubercles ; size 08 by °053 mm.: 
this form is exactly similar to that of C. nodile, but is slightly 
smaller. Spicule no. ii. bilobate, having the form of a pair of 
‘ I think it best to adopt Verrill’s term for those parts of the cortex which 
are specialized for the reception of the polypes. 
