]Mi-. W. Clark on British Mullusca. 109 



are identical with tlie Chem/iitcice), have been introduced into our 

 books, which, after a short time, are discovered to be mere varieties 

 of a particular type. 



As a final exposition of the doctrine I have mentioned, I may 

 state that it is insisted on, that the A. pes-carbonis, which presents 

 no difference but of size from the A. pes-jjelecani, is a distinct spe- 

 cies, from the fact of the two being found together, and each j)re- 

 serving its respective variatiou of major and minor. But I ask, why 

 may not a dwarf variety of a type hve with its chief as a variety, 

 without being invested with the attributes of distinctness ? The two 

 may be distinct ; but I have, I think, as good reason to believe that 

 they may be varieties of the same species. 



Rissoa jndcherrima. I have a series of this, which, I think, j)roves 

 that it is one of the endless varieties of the 11. incouspicuu. 



Cerithiojisis pulchella. I have it from JNIr. Jeffreys, and think it 

 a variety of a very variable species, the C. tuhercidaris. 



Biiccinum Hiimphreijsianum is one of the innumerable varieties of 

 B. undatum. I refer to my observations on A. pes-carbonis to show 

 that Mr. Barlee's distinctive characters are not valid. 



Triton nodiferns. Those who believe this to be a British species 

 have much more faith than I can lay claim to. 



Triton cutaceus. We must admit this species into the British list, 

 at least as a Channel Isle production, as on this day (31st of March, 

 1859) ray friend Mr. Barlee, the fortunate possessor of the identical 

 specimen mentioned in the " Gleanings," submitted it to my inspec- 

 tion at my house in Bath, and assured me that Dr. Lukis and him- 

 self personally dredged it, in a living state, off Guernsey. It is in 

 perfect condition, with the operculum, and appears to me to be less 

 than a half-grown shell. It is barely possible that it may have been 

 dropped from the bottom of a vessel from the Mediterranean : we 

 hope tiiat more examjjles may occur, to put an end to every doubt. 

 I formerlv possessed Dr. Turton's full-grown shells of this species ; 

 but I always considered them as exotic ; it is, however, stated that 

 they have on other occasions occurred in the Channel. Prof. Forbes 

 and Mr. Hanley regarded them as exotic. 



With respect to the "Gleanings" inserted in the January Num- 

 ber of the ' Annals ' for 1859, 3rd series, vol. iii. pp. 30-43, I have to 

 observe that Kellia lactea is not distinct from K. suborbicularis ; 

 the former is usually found in the mud of old bivalves, the latter in 

 the cavities of rocks ; they are mere varieties of each other. 1 find 

 no difference in their dentition. 



Lepton sulcatidum appears to be a good species — that is, on shell 

 examination. 



Mytilus Galloprovincialis, taken in the Bristol Channel*, and the 

 M. ungulatus, from the Gouliot Caves at Guernsey, both of which 

 are figured in the January Number of the 'Annals' for 1859, and 

 of the latter of which Mr. Jeffreys presented me with a specimen, 



* I have this 21st of April procured, in Bath, the finest live specimens 

 from the Scottish coasts, via Bristol ; and I have some reason to believe 

 that this mention of Bristol has been the cause of the Bristol Channel 

 being erroneously assigned as its habitat. 



