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Show 232 MR. S. O. RIDLEY ON THE CORALLIIDA. [Feb. 7, Relation of the Coralliida to other Families. The opera-glass-shaped spicule of Hemicorallium resembles strongly some forms of the " Blattkeule" (Kolliker), or foliar clavate spicule, which is found in so many species of the family Melithaida, and but unfrequently elsewhere (see Muricea, Eunicea), that I am led to believe that we have in it a hint as to the sequence of forms connecting that family with the Coralliida; and it seems to me that Pleurocorallium on the one hand, and Mopsella on the other, mark the points at which the chain of continuity between lhe families has been broken. It is true, all the Melithaida do not possess this form, or at any rate not in its typical shape ; but those which I believe to be the central forms of that family, viz. the genus Mopsella (Verrill, = Melitella and Mopsella, Gray), do show it well developed ; and it may probably be traced, though under strange modifications, hi the genus Melitodes. O n the other hand, the peculiar cylindrical form of the Coralliida appears to me to represent a highly specialized form of the fusiform or cylindrical spicule which is an almost universal constituent of the cortex of the Gorgoniida, and which occurs in a usually unspecialized form in the Melithaida also. With respect to the Isidida, their strongly calcified calcareous joints forcibly recall the hard tissue of the Coralliida, with which they are homologous; and all the spicules found in their cortex appear (see Kolliker, Icon. Histiol. p. 140, pl. xix. figs. 1-3) to be referable to a sexradiate form very closely resembling, except in its larger size, that of the red Pleurocorallium ; the separation of the hard pieces of the axis by horny joints, however, perhaps puts the family at a greater distance from the Coralliida than the Melithaida, in which these joints are already calcified. These horny joints, coupled with the absence of any spicule resembling the Melithaeid " Blattkeule," removes the family from the neighbourhood of the Melithaida ; and it probably represents a primitive offshoot from the same stem as that from which the genus Corallium s. str. has arisen. Fossil Species.-In addition to the forms described as C. pallidum and C. beckii, mentioned above under Corallium stylasteroides, and to C. nobile, also noticed above as recently recorded in the fossil state from the Italian tertiaries, it may be observed that Prof. P. M. Duncan notices, Geol. Journ. xxxi. p. 675, some fragmentary specimens from the Oligocene of Oawaru, New Zealand, and refers them to Corallium, without assigning specific names: some of these are said to possess frequently-branching furrows and ridges on their surface, much developed and very irregular in distribution; they appear to somewhat resemble parts of C. stylasteroides; but no conclusions as to specific affinity can safely be based upon them. As Corallium nobile has a white variety, and as Prof. Duncan states that he has found specimens of C. pallidum with a slight pink colour, and points out how slight are the differences between the species, I do not see how that species can be maintained as distinct from C. nobile, the colour, looser texture of corallum, and more minute stria? being the only distinctive characters given by Michelin. Seguenza (I. c.) speaks of fossil specimens of C. nobile without the |