Freshwater Mollusca of Ireland. 



31 



This very distinct and handsome species, both in form and colour, 

 is common and universally distributed in Ireland. It affects situ- 

 ations varying from very dry to very wet, and may be found on 

 rocks, under stones, fallen leaves, &c, but seems rather to show a 

 predilection for decaying wood. I have more than once detected the 

 H. rotundata in company with Limaces banqueting on some of the 

 larger Fungi. 



Specimens presenting much convexity are unfrequent, but in 

 Shane's Castle Park (county Antrim) a full-grown one has occurred 

 to me, whose height was equal to its diameter. At Holywood House 

 (county Down) I once obtained two specimens of the beautiful 

 crystalline variety. The young of this species differ very much in 

 form from the adult, in being quite flat above and very convex be- 

 neath. In the stomach of a Blackbird (Turdus Merula) , I once found 

 ten full-sized specimens of this shell, in addition to five of Achatina 

 lubrica. 



21. Helix umbilicata, Mont. p. 434. t. 13. f. 2. 



Zonites umbilicatus, Gray, Man. p. 166. pi. 5. f. 45. 

 Helix rupestris, Drap. p. 82. pi. 7. f. 7 — 9 ; Turt. Man. p. 60. 

 f.45.- 



Is commonly distributed throughout the southern three-fourths 

 of Ireland, more especially over the great limestone belt which tra- 

 verses the country: — "at its eastern commencement near Dublin, 

 and at its extreme western verge, where it dips into the ocean" in 

 the South Islands of Arran, I have found it in equal abundance. 

 This Helix attaches itself more to one kind of rock limestone than 

 any species hitherto treated of. With reference to what Montagu 

 says of its habits, it may be remarked that I have commonly col- 

 lected specimens on limestone debris resting on the ground and on 

 loose stone walls or dykes. I have not seen any Irish specimens 

 agreeing with Draparnaud's figure in tapering to the apex* ; but all 

 were of his var. " (j. testa subdepressa, umbilico latiore." Mr. 

 Gray's figure, as above quoted, is characteristic of this form ; in 

 the 1st ed. of Turton's Manual the other form was given. It is 

 Drap. var. fj. only that Mr. Jeffreys quotes (Linn. Trans, vol. xvi. 

 p. 343.), and it is this which Montagu describes ; his figure does not 

 well represent either form. 



22. Helix pygmcea, Drap. p. 114. pi. 8. f. 8—10; Turt. Man. p. 61. 



f. 46. 



Zonites pygmseus, Gray, Man. p. 167. pi. 5. f. 46. 

 This species, so interesting from its minuteness, is indigenous to 

 the more northern two-thirds of Ireland from east to west, and 

 doubtless will be found by him who searches properly for it in the 

 south. It is partial to shade and moisture, under stones in pastures 

 may be procured, but is most readily and frequently obtained on fallen 

 leaves, &c. in plantations. Since the Mollusca first claimed my 



* Draparnaud's figure is very characteristic of specimens sent me from 

 France by M. Michaud. 



