Clare Island Survey — Land and Fresh-water Mollusca. 23 46 



but all the remaining central species found at Castle bar occur also in the Clew 

 Bay area. Westward of this they are conspicuous by their absence, except 

 in the coastal lakes south of Louisburgh, where some of them make 

 their reappearance. That these outliers once upon a time lived in direct 

 communication with the main body is perhaps possible. 



The sudden disappearance of the members of the central fauna, as one 

 proceeds from Newport towards Mulranny, has been commented upon by 

 J. 6. Milne (Journal of Conch., vi, 412-421, 1891), and is worthy of 

 notice. Thus, my list for Creevaghaun Lough comprises (besides universally 

 distributed species such as L. pereger) A. hypnorum, PI. albus 

 P. crista, P. fontcmus, V. cristata, B. tentacidata, S. corneum, P. 

 obtusale, P. pusillum, and P. milium ; that from Dougan Lough, 

 L. stagnalis (a peculiaiiy stunted form), PI. albus, P. contortus, P. spiroriis, 

 B. tentacidata, V. cristata, P. cascrtanum, P. lilljeborgi, and P. milium ; 

 while from Lough Arrow, 1 collected by F. Balfour Browne, I have 

 A. hypnorum, P. fontinalis, PL contortus, P. fontanus, B. tcntaculata, and 

 S. corneum. All these lakes lie to the east or south of Newport, and contain 

 a curious mixture of central and western shells. With the exception of 

 P. contortus, which occurs in a small lakelet near Burrishoole Abbey, none of 

 the central species has been reported west of Newport ; and Bunnamucka 

 Lough, a small lake near Rosturk, contains only L. pereger, L. truncatula, 

 PI. crista, and P. milium, P. subtruncatum, and P. pusillum, which, if 

 L. palustris and P. glabcr were present, might be looked upon as a typical 

 fauna for a small western lake. 



In the southern part of the district the local distribution of the central 

 members of the fresh-water fauna is similar to that around Newport, as eight 

 of these occur in the Carrowbeg at Westport, aud none in the 18 miles of 

 country which lie between this town and the nearest of the Louisburgh lakes. 

 The problem which requires to be solved in connexion with these species is 

 whether they have once had a wide western distribution and have since 

 retired to the central plain, or whether they have endeavoured to spread from 

 the central plain in post-Glacial times ? The finding of deposits underlying 

 the peat-bogs might solve this, and it is to be regretted that the study of 

 these deposits has been greatly neglected. 



The terrestrial species of the central type are, in this district, limited 

 to three — Pyramidida rupestris, Hygromia rufescens (probably introduced by 

 man), and I include Succinea ptdris — these exhibit a local distribution 

 somewhat similar to the fresh-water species of the group. The two former 



1 This must nut be confounded with the larger L. Arrow in Co. Sligo. 



