236 DUBLIN UNIVERSITY 



The four specimens that I have above described have been in- 

 trusted to me by my kind friend, Dr. E. Perceval Wright, of the Dublin 

 University, with whose name I have honoured the species. They were 

 dredged by G. C. Hyndman, Esq., among shell sand, from a turbotbank 

 off the coast of Antrim, in 1852. 



It is an interesting question, particularly to myself, whether these 

 specimens belong to a fossil or a still existing species. If the latter 

 alternative prove to be true, it further augments the already rich and 

 constantly enriching zoophy tology of our insular coasts. Professor Milne 

 Edwards, indeed, considers the Sphenotrochi with papillate and crisped 

 costae to be in no case later than the Eocene deposits ; while those with 

 smooth costae as invariably belong to higher strata, and reach to the 

 present period : but this is a canon which a new species may at any 

 moment overturn, if it be not already subverted by the S. nanus (Lea) 

 of the Eocene of Alabama. Dr. E. P. "Wright mentions as a suspicious 

 circumstance that many Pleistocene shells do exist in the bed of shelly 

 sand, where these specimens were found. But this does not confirm 

 Professor Milne Edwards's rule ; for, so far as that could decide the 

 question, it would prove not only that the coral is not recent, but that 

 it is certainly as old as the Miocene. 



Dr. Wright says : — " I have reason to think, however, that they are 

 not fossil ;" and the same is my own impression, though I can scarcely 

 assign any definite grounds for it, except the fresh appearance of one or 

 two of the specimens. Some of them are rubbed ; and one (Fig. 4) is 

 polished externally. 



The uniformity in size of the individuals, and the full development 

 of the septa, indicate a probability that, minute as they are, they have 

 attained adult age. 



Explanation of Plate XXV. 



Fig. 1. Sphenotrochus Wrightn, magnified 12 J diameters; view of the 



broader side. 

 Fig. 2. Ibid., magnified 25 diameters; vertical aspect of the calice. 

 Fig. 3. Ibid., the same specimen as Fig. 1, similarly magnified; view of 



the narrower side. 

 Fig. 4. Ibid., another example, magnified 12 J diameters; the broad 



side. 



