RECORDS OF DISTRIBUTION OF MOLLUSCA. 183 
referee are well known; or they are slugs, for the deter- 
mination of which Mr. Roebuck himself, who has made 
a special study of the naked species, is responsible. 
It does not follow that other records are not equally 
reliable, but for the sake of uniformity of value it is— 
as will be at once obvious—necessary to confine the 
tables to such records as have been submitted to and 
passed by the society’s referees. Otherwise a wide door 
would have been opened to errors of determination, the 
avoidance of which is the object aimed at in instituting 
the authentication system. 
The areas adopted are those proposed by Mr. H. C. 
Watson, and used by him in working out the distribu- 
‘tion of the British Flora. 
It is deemed sufficient to confine the tables to the 
distribution of species, that of varieties being for many 
reasons impracticable at the present time. 
Readers who can furnish specimens for completing 
these tables will do well to send them to Mr. W. 
Denison Roebuck, F.L.S., Sunny Bank, Leeds, as he 
will for the present continue to keep the records and 
submit the specimens sent to the referees. 
