On the Classification of Marine Testaceous Mollusca. 469 



O. tw-rita (mihi) is the striolata of Alder, to whom a specimen 

 was lately sent for his inspection and confirmation. 



O. plicata. Guernsey (Mr. Barlee) . It appears to be an uni- 

 versally distributed species. 



O.conspicua. Loch Fyne (Angus M'Nab). I observed a fine 

 specimen last spring in the collection of Sig. Nardo at Venice, 

 from the Adriatic. The authors of the ' British Mollusca say it 

 is allied to, if distinct from, conoidea ; but Mr. Clark, quoting 

 them, refers it to acuta ! 



O. diaphana is more cylindrical than ohliqm, and the whorls 

 in young shells of each preserve the same relative proportions. 



O. obliqua. All the localities given in my first paper, except 

 Burrow Island, belong to this species, which I at that time re- 

 garded as identical with Warrenii or decorata. 



O. Warrenii. Falmouth and Zetland (Mr. Barlee). 



O. [Eulimella) affinis. Zetland, the same. 



I am. Gentlemen, your very faithful servant, 



J. GwYN Jeffreys. 



XLVII.— On the Classification of the British Marine Testaceous 

 Mollusca. By William Clark, Esq. 



To the Editors of the Annals of Natural History. 

 Gentlemen, Norfolk Crescent, Bath, May 1850. 



It will be convenient, with reference to my papers on the British 

 Marine Testaceous Mollusca which have appeared m the An- 

 nals,' that a synopsis of the classification of the whole tribe 

 should be submitted, accompanied by a short analysis, that the 

 incidents and position of any particular family may at once be 

 examined. Most naturahsts have their own plan of distribution 

 with respect to natural order ; perhaps then, I shall not incur 

 the imputation of an unmeasured presumption, if I venture to 

 offer a sketch of mine, founded on forty years' sedulous investi- 

 gation of our indigena. I have not the vanity to suppose my 

 scheme is superior to the methods of my brethren ; but it is novel, 

 and exhibits, as I think, a progressive advancement ot animal 

 organization and harmony of arrangement from the beginning ot 

 the class to its termination, by which groups of similar affanities 

 are insensibly united as far as is possible, and succeed each other, 

 on the bases of external and internal anatomical considerations 

 These memoirs are the result of numerous visits to the bouth 

 Devon coast at Exmouth, where I have passed my leisure m the 



