127 
NOTES ON THE AUTHENTICATED COMITAL DIS- 
TRIBUTION OP SCOTTISH LAND AND FRESH- 
WATER MOLLUSCA. 
By VVm. Denison Roebuck, F.L.S. 
1. 
IN continuation of the " Census of Scottisii Land and Fresh- 
Water MoUusca," which was pubHshed recently in the 
Proceedings of the Royal Physical Society of Edinburgh, I propose 
to publish from time to time in the Scottish Naturalist, under the 
above title, such further notes on the comital range of Scottish 
land and fresh-water moUusca as the kindness of Scottish natural- 
ists may enable me to, and already I have, through the kindness 
of Mr. J. Charles Smith of Penrith, and of the Rev. J. McMurtrie 
of Edinburgh, some much-needed additional records to bring 
forward, and through the kindness of Mr. Bennie an important 
note bearing on the right of Li7jincea stagnalis to be regarded as 
native in one of its authenticated habitats. 
Before giving these, however, it is incumbent upon me to say a 
few words in reference to the adverse criticisms of Dr. Buchanan 
White which appear on another page. Dr. White not only prunes, 
the branches of my tree but he also lays his axe to the root, in 
his notes, and I must do what I can to make* matters clear in 
respect to the various points to which he refers. His most im- 
portant criticisms are those regarding my adoption of Mr. Cottrell 
Watson's botanical vice-counties instead of Dr. White's own river- 
basin areas, and my confining myself to the authenticated records 
of the Conchological Society instead of including all pubUshed- 
records. 
With regard to the latter point, I had imagined that I had made 
myself sufficiently clear in my Census " that it simply dealt with 
authenticated records. The great advantage of this is, that my 
paper, instead of being of unequal value (as printed records in 
the mass necessarily must be), is of uniform and equal value 
The determination of the species or variety of each of the numer- 
ous records I published is exact and reliable, and, therefore, 
every record can be quoted with confidence. 
No one will imagine for a moment that I doubt the genuii e- 
