23 48 Proceedings of the Royal Irish Academy. 



Some common species are absent from the above list. This is, lio dOubt, 

 clue to insufficient work, as I was unable to devote much time to this 

 district. 



9. ALTIDUDINAL DISTRIBUTION OF SPECIES. 



No great amount of work has been done in this direction by British 

 conchologists, but several interesting papers dealing with it have nevertheless 

 been published. 1 



From a purely conehological point of view, a day's work which perhaps 

 only yields Arion ater, Limax arborum, and a severe drenching in mist, might 

 be considered unproductive. I can express from experience a feeling of 

 sympathy with those who regard the subject from that point of view, but if a 

 list of a dozen or more species can be compiled at an elevation of a thousand 

 feet above the sea, the interest attached to such should amply compensate 

 one for the exertions expended. A complete list of the mollusca found in 

 Ireland at an altitude over 1,000 feet will, I think, be found closely to 

 resemble a list of the molluscan fauna of the western islands, with this 

 difference, that the xerophytic species will be absent. These xerophiles being 

 all southern species, or having their headquarters in the south of Europe, it 

 might be imagined that this "alpine" list would include only northern 

 species. This is, however, not the case, as a fair proportion of those mollusks 

 met with on our mountain-tops are typical Lusitanians. Thus Milax gagates 

 lives on the summit of Brandon in South Kerry, one of the few mountains in 

 Ireland which exceed 3,000 feet in height. Dr. Scharff has pointed out 2 that 

 the members of the genus Arion are Lusitanians, yet three of the five 

 species found in Ireland are almost universally met with on our highest 

 mountains. 



Confining ourselves to the district included in the Clare Island Survey, we 

 find that suitable habitats for mollusca, at an altitude exceeding 1,000 feet 

 are few in number and restricted in area. Moreover, the mountains being 

 almost entirely composed of non-calcareous rocks, smoothed by glaciation, and 

 covered with accumulations of peat, our alpine list would be small indeed 

 were it not for the great sea-cliff of Croaghmore on Clare Island. Except for 

 the two species of Pisidia in the following list, and Ancyhis fluviatilis, all are 



1 Scharff and Carpenter: "Some Animals from tlie Magillicuddy's Reeks." Irish Nat.,v'iii, 

 213-218. 1899. W. Harcourt-Bath : " On the vertical and bathymetrieal distribution of the non- 

 marine mollusca, with special reference to the Cotteswold fauna." Zoologist (4), xiii, 41-53. 1909, 



■ European Animals, p. 90, 



