70 



The Irish Naturalist. 



May, 



most of the information regarding the present fauna, its 

 characters and its distribution. Apart from the labour of 

 working out the mass of material, the authors' most 

 valuable contribution is the comparative knowledge which 

 they were able to bring to bear, linking up the Continental 

 and English forms with those of Ireland. 



The special importance of the land mollusca in distri- 

 butional studies has long been recognised ; this is due to their 

 comparatively sedentary character and to their specializa- 

 tion as regards habitat. It was for this reason that Dr. 

 Scharff commenced some thirty years ago the detailed 

 study of their Irish distribution, which resulted finally in 

 the production of Mr. Stelfox's well-known census, published 

 in 191 1. The authors of the paper under review are careful 

 to emphasize the same fact. The fresh- water species appear 

 on the whole to possess much greater means of dispersal, 

 and are therefore of somewhat less value for distributional 

 studies : at the same time, the best sections as well as the 

 most numerous, are those of old lake deposits ; sections 

 yielding land species, such as those found among sand-dunes, 

 in caves, raised beaches, or river deposits, being less fre- 

 quently met with, or less easy to work, or less satisfactory 

 from a stratigraphical point of view. Although the present 

 paper is a record of much accomplished, it is clear that 

 as regards the study of both land and water deposits only 

 a beginning has been made, and it is to be hoped that now^ 

 that the living fauna is so well known, Irish conchologists 

 will concentrate on the study of the past history of the group, 

 which when fully elucidated ought to provide invaluable 

 evidence bearing on the much-debated question of the age 

 and origin of the fauna and flora of our country. 



In the present paper results are given of the examination 

 of y^ sections, which are classified as follows : — 



2 



