276 THE SCOTTISH NATURALIST 



sheep, etc., to and from the mainland, one could not but 

 wonder how far cattle had been responsible for the existing 

 fauna. 



Mr Dyke remarks that geographically the Lewis is 

 divided into two parts by the road from Callernish to Luir- 

 bost ; to the south are the hilly districts of Park and Uig, 

 and to the north the flat parishes of Barvas and Stornoway. 

 Except for the plantations round the Castle at Stornoway, 

 the island is practically a treeless waste, a circumstance 

 which does not tend to produce conchological paradises. So 

 also with the general absence of lime in the soils, which 

 tends to thinness of texture in the shells. 



The investigation of the mollusca of this vice-county 

 has been in very few hands. 



The earliest record I have confining attention exclu- 

 sively to " authenticated " specimens is that of Helicella 

 itala in Harris, seen in 1884 in the Alder Collection at 

 Newcastle. 



My old friends the Somervilles of Glasgow investigated 

 in the years 1886 to 1888. A. Somerville worked the Lewis 

 in 1886, South Uist and Barra in 1887-88, and his brother, 

 the Rev. J. E. Somerville, Barra in 1886-87, the Lewis, 

 Benbecula, and South Uist in 1886. Their specimens are 

 now in the possession of their nephew, the Rev. G. A. 

 Frank Knight, along with those of his own collecting. 



I have one record by David Robertson, specimens in the 

 Kelvingrove Museum at Glasgow, and in 1894 Thomas Scott 

 collected some species of freshwater shells on North Uist and 

 Barra. 



In 1904 Dr W. Eagle Clarke sent me Avion ater from 

 the Flannan Islands, an interesting outlier of the main 

 archipelago. 



In 1905 Mr James Waterston visited North Uist and the 

 interesting St Kilda group, publishing a paper on his results 

 the following year. 



Lastly, in the present year (191 8) Mr F. Montague Dyke 

 collected the Lewis shells which were the incentive to the 

 writing of this paper, and it is a pleasure to add that the 

 material upon which, so far as concerns Lewis, this paper is 



