Freshwater Mollusca of Ireland. 



19 



3. L. agrestis, Linn. Gray, Man. p. 117. 



This, the small rough yellowish species, is very common through- 

 out the north, and I believe in Ireland generally. 



4. Limax 



The Rev. B. J. Clarke, of Merrion Square, Dublin, has favoured 

 me with a coloured drawing and a description of a Limax which he 

 has taken at La Bergerie, Queen's county, and describes to be "black- 

 ish-grey on the back, lighter underneath, with a sharp keel down the 

 back proceeding from the shield." It may be the L. carinatus, 

 Leach, or L. gagates, Drap. ; but not having seen any specimens, I 

 abstain from naming it even with a mark of doubt. 



2. Vitrina. 



V.pellucida, Drap. p. 119. pi. 8. f. 36, 37. Gray, Man. p. 120. 

 pi. 3. f. 21. 



Is in suitable localities distributed over Ireland, and maybe found 

 under the first stones we meet with in going inland from the sea- 

 shore, up to as great an altitude in the mountain glens as there are 

 moss and leaves to shelter it. I have remarked the colour both of 

 animal and shell to vary, and the latter to present some differences 

 in form. See Jeffreys on V. Mulleri and V. Draparnaldi in Lin- 

 nsean Transactions, vol. xvi. When thin and of an almost crystal- 

 line transparency, the shell is often more handsomely formed than 

 when thicker and of a greenish colour, and is intermediate between 

 the V.pellucida and V. diaphana, «as represented by Draparnaud 

 (pi. 8.) and Rossmasslcr (t. 1.) ; this state is equally common with 

 the normal V. pcllucida ; of this, the animal is lighter in colour, and 

 'not so large compared with the shell as in the variety*. 



3. Testacella, Cuv. 

 Testacellus haliotideus, Fer. Gray, Man. p. 124. pi. 3. f. 19, 20. 

 Testacella haliotidea, Drap. p. 121. pi. 8. f. 44, 45. 



This species was discovered many years ago hy Mr. R. Ball in the 

 town gardens at Youghal, where it has become much scarcer of late. 

 The Irish specimens agree with English examples of the var. V. scu- 

 tulum, with which I have been favoured by Mr. G. B. Sowerby. 

 Mr. Gray (Man. p. 123, 124.) seems to consider this a naturalized spe- 

 cies, but the circumstance of its being found at Youghal speaks 

 more strongly in favour of the T. haliotideus being a true native 

 than that of its being met with in some of the gardens around 



* Most of the very numerous species of land mollusca which I find on the 

 fallen leaves of trees are particularly partial to those of the Scotch elm (Ul- 

 mus montana) ; when the large and rough leaves of this tree are mingled 

 with those of the common forest or ornamental kinds, I have observed that 

 about twenty specimens may be found on them, for one on an equal propor- 

 tion of any of the others. When the ground is saturated with moisture the 

 cause of this preference is obvious, as the nerves of the leaves are so strongly 

 developed, that when the under side is next the ground the membranous 

 portion of the leaf between them remains quite dry. 



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