232 MR. S. O. RIDLEY ON THE CORALLIID^. [Feb. 7, 



Relation of the CoralUida to other Families. 



The opera-glass-shaped spicule of //e/wieora///'Mm resembles strongly 

 some forms of the " Blattkeule " (KolUker), or foliar clavate spicule, 

 which is found in so many species of the family MelithceidcB, and but 

 unfrequently elsewhere (see Muricea, Eunicea), that I am led to 

 believe that we hare in it a hint as to the sequence of forms connecting 

 that family with the Coralliidm ; and it seems to me that Pleuroco- 

 rallium on the one hand, and Mopsella on the other, mark the 

 points at which the chain of continuity between Ihe families has been 

 broken. It is true, all the Melithceidce 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, Gra.y), do show it well developed; and it 

 may probably be traced, though under strange modifications, in the 

 genus Meliiodes. On the other hand, the peculiar cylindrical form 

 of the Coralliidce uppeRTS to me to represent a highly sjiecialized form 

 of the fusiform or cylindrical spicule which is an almost universal 

 constituent of the cortex of the Gorgoniidce, and which occurs in a 

 usually unspecialized form in the MelithaidcB also. 



With respect to the Isididae, their strongly calcified calcareous 

 joints forcibl}' recall the hard tissue of the CoraltiidcE, with which they 

 are homologous ; and all the spicules found in their cortex appear 

 (see KoUiker, Icon. Histiol. p. 140, pi. 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 Goralliidce than the Melithaidce, in which 

 these joints are already calcified. These horny joints, coupled with 

 the absence of any spicule resembling the Mehtiiseid " Blattkeule," 

 removes the family from the neighbourhood of the MelithceidcB ; 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. pnllidum 

 and C. becJiii, 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 speci- 

 mens 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 con- 

 clusions 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 strise being the only distinctive characters given by Michelin. 

 Seguenza (I. c.) speaks of fossil specimens of C. nobile without the 



