l86 The Irish Naturalist. October, 



appears to be absent, though no reason for this can be 

 given; but as no really natural habitat for fresh-water 

 species occurs on the island during dry weather P. personatum 

 could not be expected to find a dweUing-place. The 

 remaining six species should occur, and it is just possible 

 that the dry summer of 191 1 and the drought during April 

 and May, 191 2, may have caused a temporary shortage, and 

 hence a second visit to the island might reveal their presence. 

 The five unexpected species found were Li max maximus, 

 L. cinereo-niger, Sphy radium edentulum, Helicella virgata and 

 H. inter seda. All of these occur on the opposite mainland. 



Since Mr. Praeger has described already (pp. 157-158 

 supra), the main features of the Great Blasket I need not 

 repeat these. The chief points from a conchologist's point 

 of view are, however, as follows : — 



(a) A quick run-off of rain and hence want of standing 

 water. 



{h) The crumbUng nature of the north-western cliffs, 

 well shown in the two photographs on plate 3, 

 and therefore scanty vegetation and httle shelter 

 for mollusca. 



(c) The destruction of the vegetation by grazing sheep 

 over the greater portion of the island ; and 

 also by wind and sea along the western and 

 south-western slopes, which are very dry and 

 bare. 



{d) The influence of man appears nil, and no species 

 seems to have been artificially introduced. 



LIST OF SPECIES FROM GREAT BLASKET. 



Limax maximus L. — A single very large specimen, slightly paler than 

 the type in colour, was taken at dusk just emerging from its retreat 

 beneath one of the thousands of rock -slabs scattered over the slopes 

 between Garraun Point and Canknock, near the north-eastern corner 

 of the island, at an altitude of about 250 feet. This specimen is the 

 first example of L. maximus which I have taken on any of the western 

 islands in an undoubtedly native habitat, all others having been 

 observed within the precincts of habitations. I cannot agree with 

 Dr. Scharffi that we must look upon a specimen as a native unless 



1 See note owTestacella haliotidea, supra, p. 155. 



