LAND AND FRESH-WATER MOLLUSCA FROM BUTE. 125 



VIII. 



NOTES ON SOME SPECIES OF LAND AND 

 FRESH- WATER MOLLUSCA AND LAND 

 ISOPODA FROM BUTE. 



BY THOMAS SCOTT. 



[Read 29th March, 1887.] 



Mollusc a. 



Planorbis glaber, Jeffreys (=P. parvus, Say). — 

 This fresh-water snail has, according to Dr. Jeffreys, 

 a distribution co-extensive with Great Britain, or, 

 in his own words, "from Burra Fiord in Unst to 

 Penzance " ; but according to the same author " it 

 is not generally diffused." In Scotland its distribu- 

 tion seems to be very restricted. It has been found 

 in Unst, one of the Shetland Islands, as recorded by 

 Dr. Jeffreys ; and its occurrence in West Sutherland 

 is recorded by Messrs. J. W. Taylor and W. Denison 

 Roebuck, F.L.S., in the " Census of the Authenticated 

 Distribution of British Land and Fresh-water 

 Mollusca" (See Journal of Conchology for 1885). So 

 far as I can discover, however, these are the only 

 authentic records of its occurrence in North Britain ; 

 and it is the more interesting, therefore, that we 

 are now able to add it to our list of Clydesdale 

 molluscs. 



The only place where I have found it, as yet, is 

 in Greenan Loch, near Rothesay, and there it seems 

 to be somewhat scarce. I first noticed it on the 

 28th of January, 1887, and have since obtained 

 additional specimens from the same loch. The 

 specimens are not very large, but better may be 

 found further on in the year. It is, however, a 

 small species, for Dr. Jeffreys refers to one " nearly 

 a quarter of an inch in diameter" as being the 

 largest he had ever seen. 



