126 Mr. Jeffreys on British Mollusca. 



Skye and Guernsey, and Mr. M 'Andrew has it from the Mediterra- 

 nean. A specimen, larger than usual, confirms the idea I entertained 

 from the first, that this is Philippi's species. 



Paludina vivipara, iii. 11. A young specimen occurred to me in 

 the Guernsey dredgings ; but how it got there is a marvel. Dr. Lukis 

 assures me that there is no river in any of the Channel Isles, nor 

 indeed any piece of water in which such a shell is likely to exist ; 

 and he has never found a Paludina, after many a diligent search 

 for freshwater shells in that district. The specimen above mentioned 

 may possibly have been transported by some river from the opposite 

 coast either of England or France ; the specific gravity of fresh water 

 being less than that of the sea, its motion might buoy up such 

 trifling substances for a long distance. 



[In a letter which I have received from Dr. Lukis since writing the 

 above, he offers a more probable solution of the problem, in suggesting 

 that the shell may have been brought in ballast ; and he says that 

 some years ago, certain individuals, who were more adventurous and 

 speculating than wise, opened a vein of black oxide of manganese in 

 the neighbourhood of the dredging-ground, conceiving it to be a vein 

 of plumbago, and that vessels came, no doubt in ballast, to remove 

 the supposed treasure, and possibly left the shell in question to puzzle 

 future speculators. I may remark, in confirmation of this idea, that 

 I found, with the Paludina, some Foraminifera (species of Rotalina 

 and Nummulina) which are evidently fossil, and may have been also 

 brought from Sheppey or the Isle of Wight.] 



Lacuna crassior, iii. 67. In dredged sand from Guernsey. 



Rissoa Beanii, iii. 84. With the last. 



R. cimicoides, Forbes, iEgean Invertebrata in Brit. Assoc. Rep. 

 for 1843, p. 189. R. sculpta, B. M. iii. 88 (not of Philippi). Guern- 

 sey, with R. calathus. A comparison of typical specimens of R. ci- 

 micoides, in Mr. M'Andrew's collection, with our shells and the 

 author's description, induces me without any hesitation to refer the 

 R. sculpta of the authors of the 'British Mollusca' (founded on my 

 specimens) to the above species. Philippi's species is evidently dif- 

 ferent, the longitudinal ribs and cancellation being more remote, and 

 the inner lip smooth, in his shell. On this last character he indeed 

 lays particular stress in comparing it with other species ; and it is 

 very distinct in our shell, 



R. punctura, iii. 89. Guernsey (Dr. Lukis & J. G. J.). 



R. rufilabrum, iii. 10G. In dredged sand from Guernsey. 



R. inconspicua, iii. 113. With the last. 



R. vitrea, iii. 125. Torbay and Plymouth. 



R. proxima, iii. 127. With the last ; thus affording a corroborative 

 proof that the two species are distinct. 



R. pulcherrima, iii. 129. Paignton, at the rocks of Corallina 

 officinalis. This cannot easily be mistaken for any of the numerous 

 varieties of R. inconspicua (which is also found in the same locality), 

 being so very different in form and markings. 



R. soluta, iii. 131. In dredged sand from Guernsey, not uncom- 

 mon ; and in trawl-refuse from Plymouth. 



