22 Mr. Goodsir on the Anatomy of the Limncus involutus. 



V. — Description of Limncus involutus, Harvey, MS. By 

 W. Thompson, Vice-President of the Natural History So- 

 ciety of Belfast ; — with an account of the Anatomy of the 

 Animal. By John Goodsir, Esq. 



[With a Plate.] 



Limneus involutus, \ti. t \fo 

 Amphipeplea involuta } J L J' 



Spec. Char. Spire sunk within the outer whorl ; aperture 

 very large, extending to the apex. 



The finest specimen I have examined is 5| lines in length, 

 and 3jL in breadth ; volutions four, the largest enveloping the 

 other three, of which none are visible in the profile of the 

 shell ; aperture very large, wide at the base (exposing the co- 

 lumella throughout its entire length) and extending to the 

 apex of the shell, margin reflected only where it joins the pil- 

 lar. Shell polished, of a pale amber colour, extremely thin, 

 with coarse longitudinal striae. 



This species approaches the L. glutinosus more nearly than 

 any other native Limneus, but from the circumstance of the 

 aperture extending to the apex, has at a cursory view as great 

 a resemblance to the Bulla Akera, Mont., as to any other Bri- 

 tish shell ; a coincidence which is rendered still more remark- 

 able by the columella presenting the same appearance in the 

 L. involutus as it does in that species. 



The discovery of this new and beautiful mollusk is due to 

 my friend Wm. H. Harvey, Esq. (well known for his botanical 

 investigations) who obtained a few specimens in a small alpine 

 lake on Cromaylaun mountain, near the celebrated lakes of 

 Killarney, in the month of April 1832. 



The above account was read to the Linnaean Society of Lon- 

 don in April 1834. To the present time (Sept. 1839), I have 

 not heard of the occurrence of the species in any other locality 

 in Ireland. The original station was visited by Mr. R. Ball 

 and myself in June 1834, when we procured only a few small 

 specimens. The time was however unfavourable for seeing 

 these mollusks to any advantage, being at a very early hour in 

 the morning, before the warmth of the sun had tempted them 

 to leave the bottom of the lake or adjoining rivulet. 



This shell, from partaking more of the form of the marine 



