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ON EUKTIMINARIA DUCALIS.

BY THE REV. J. E. TENISON-WOODS, F.G.S., F.L.S.

In the Proceedings of this Society last year, I described (Vol. III., p. 126) what I considered to be a new genus of Polyzoa under the above name. I mentioned that similar fossils had been found in the chalk, and that M. d'Orbigny had suggested that

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they were Comatulae without arms. I am now convinced that this explanation of these bodies is the correct one. They are the central disks of some unknown species of Comatulae. I have seen a central disk of an undescribed species, which though much smaller and with very much fewer pores, yet is so similar in all other respects that I do not doubt my Euktiminaria ducalis, the Glenotremites paradoxus of Goldfuss, the Decamerus mysticus of Hagenow, are all central disks of Comatulae. The central pores on each of these organisms which bear so close a resemblance to the cells of Polyzoa are doubtless connected with the water circulation, like the madreporiform bodies in the Echinodermata. They are not present in all the Comatulae, at least in this form.