7318 Mollusks. 



Lampern {Petromyzon Jluvialis). One specimen. Included in this list because 

 not generally supposed to visit, at any season, the salt water. — Edward T. Higgins ; 

 101, Kingsdown Parade, Bristol, November 27, 1860. 



The new British Physa. — The announcement (Zool. 7278) of a Physa new to the 

 British fauna will be received with interest by many readers of the ' Zoologist.' But 

 they will probably agree with me that certain points in Mr. Choules's statement 

 demand further elucidation before the species can fairly take rank as a Brilon. 

 From the days of Turton and Montagu the fresh-water Mollusca have received so 

 much attention, and the species, with one or two exceptions, are so well known and 

 generally distributed, that the fact of one having been overlooked might be regarded 

 as well nigh impossible. I am not aware that any addition has been made to them 

 since Dr. Harvey found Amphipeplea involuta ; or Mr. Bean, Pisidium cinereum. 

 Moreover, when we consider the number of West-Indian species which have been 

 enumerated as British, and then rejected on irrefragable evidence, we cannot but fear 

 that Mr. Choules's Physa may share their fate. After all, there appears to be a degree 

 of uncertainty as to the species his has found. According to Forbes and Hanley, vol. 

 iv. pp. 143, 144, the Physa rivalis of Maton and the Physa acuta of D'Orbigny and 

 Draparnaud are distinct, the former being West Indian and the latter European. 

 Both have already been described as British, and rejected as spurious. To which of 

 them are we to refer Mr. Choules's mollusk? Again, the habitat in Kew Gardens 

 must be regarded with suspicion. It is true that the extreme delicacy of the Physa 

 would render it unlikely that it has been introduced with water-plants from a foreign 

 country ; still it is possible that such might be the case, and in our ignorance of the 

 locality where Mr. Chuules at lirst collected his specimens we are at liberty to con- 

 'jecture that they may have originally found their way to both stations from accidental 

 causes. Would it not be desirable to entrust the secret of their whereabouts to one 

 or other of our eminent conchologists ? If Mr. Jeffreys, or Mr. Norman, or Mr. 

 Woodward, were to investigate the spot, and declare the shell to be British, it would 

 be universally accepted as such, and prove a highly interesting addition to our fauna. 

 I think we might venture to promise Mr. Choules that none of these gentlemen would 

 extirpate the race. Once more: will not some readers of the ' Zoologist' apprehend 

 that this shell may, after all, prove an extreme form of our Phjsa fontinalis ? I am 

 unacquainted with either of the foreign species in question, but can verify the obser- 

 vation of Forbes and Hanley, vol. iv. p. 142, that British varieties of Physa fontinalis 

 " differ as much from the typical form as many of the supposed species of Physae do 

 from each other." It appears also that a confined area, like the lank in Kew Gardens, 

 has a tendency to affect the growth of these shells, and in particular to develop their 

 spire to an unusual extent. Far be it from me to throw discredit on Mr. Choules's 

 discovery. Having myself paid some attention to our fresh-water Mollusca, I am 

 ready to admit that they possess a mysterious faculty of finding their way to unlikely 

 habitations. Every naturalist can cite examples of Dreissena polymorpha turning up 

 profusely in waters where it had hitherto been unknown, and whither its progress could 

 not be traced. I have myself collected a dozen species of shells in a pond at North 

 Stainley, near Ripon, which is at least half a mile from any other water. Two of these 



