108 



Proceedings of the Royal Irish Academy. 



LmifAEIDAE. 



Ancylus fiuviatilis Miiller. 



Patella lacudris, Brown, Mem. "Werner. 

 Soc, vol. ii, p. 533, 1818. 



WD ED LD AN 

 FE TY AR DO 

 WMSL LE MO 



EM RO CV LH 

 WG NG LF WH ME 

 SG KG KD DU 

 CL NT QC GW Wl 

 NK LK ST KK WX 

 SK MG EG WA 

 WG 



Abundant in all the mountainous 

 parts of the country, but rare in many 

 parts of the central plain, though very 

 generally distributed. This shell shows 

 great variation in size and shape, in 

 texture, and other characters. As u 

 general rule our Irish specimens are 

 small ; hut in lakes with stony edges and 

 bottoms fair-sized shells are often met 

 with. In such a lake in Co. Down 

 Mr. J. N. Milne has taken some parti- 

 cularly fine white examples, quite equal 

 in dimension to the largest specimens I 

 have seen from other countries. 



Ancylus fluviaiilis is common in 

 streams on Clare Island and in the 

 lakes of Achill in West Mayo, and 

 has also been taken in a lake on Clear 

 Island in West Cork. 



A strongly striated form, similar to 

 the Ancyltis striatus of the Atlantic 

 Islands, which according to Wollaston 

 may be regarded as a geogi'aphioal 

 phasis of the present species, occurs in 

 several places along the west coast. 



A sm;ill form is exceptionally abun- 



dant in the highest of the small tarns 

 on Brandon Mountain in South Kerry, 

 which lies at an altitude of 2300 feet. 

 This small form is that which is 

 commonly met with in peaty waters. 



Acroloxus lacustris (Linne). 



Patella ollonga, Brown, Mem. Werner. 

 Soc, vol. ii, p. 533, 1818. Ancyltis 

 lacustris, Thompson, Cat. L. & F. W. 

 Moll, of Ireland, p. 33, 1840. 



WD ED LD AN 



FE TY AR DO 



WMSL LE MO 



EM EO CV LH 



WG NO LF WH ME 



SG KG KD DU 

 GL NT QC CW wi 

 NK LK ST KK WX 



SK MC EC WA 

 WC 



Like many of our rarer freshwater 

 species, this is mainly confined to the 

 central and north-eastern districts, and 

 there are no records for the more moun- 

 tainous and non-calcareous districts of 

 the south, west, and north. Species 

 which have a somewhat similar range 

 in Ireland are Zimnaea stagnalis, Plan- 

 orbis carinatus, P. umhilicatus, and 

 Anodonta cygnea. 



Limnaea auricularia (Linne). 



Plate VII, figs. 15-20. 



Selix auricularia, Brown, Mem. Werner. 

 Soc, vol. ii, p. 531, 1818. Limneus 

 auricularius, Thompson, Cat. L. & F. 

 W. Moll, of Ireland, p. 29, 1840. 



Though widely distributed through- 

 out Ireland, this shell is always local 

 and seldom really common, except in 



