278 TRANSACTIONS. NATURAL HISTORY SOCIETY OF GLASGOW. 



adopt in toto. They resolved, therefore, to make the anatomical 

 system of Pelseneer their general basis, but in all groups to adopt 

 the classification of individual workers who had specialized in 

 their particular departments. The new classification thus 

 established led to many transpositions of genera and species from 

 the old standard of Jeffreys. 



III. Nomenclature. — All previous workers in the compilation 

 of lists, and all writers on the Mollusca of Britain, had taken the 

 12th Edition of the Sy sterna Natures of Linne (issued in 1767) as 

 the terminus a quo of the binomial nomenclature. The Com- 

 mittee felt bound to follow the recent trend of science, and to go 

 back to the 10th Edition, which was published in 1758. Following 

 the law of priority of nomenclature, they had to relinquish many 

 time-honoured names, and to substitute titles which had claims 

 to precedence. But wherever a change of this sort was necessary, 

 the former familiar name had been enclosed within square 

 brackets. 



IV. Insufficiently attested species. — The Committee felt bound 

 to be somewhat severe towards many doubtful claimants for 

 recognition, and in many cases a number of varietal names, 

 apparently based on monstrous, stunted, aborted, or young 

 specimens, had been omitted. Exotic migrants, and recent- 

 looking post-tertiary shells had also to be carefully distinguished 

 from the legitimate ones. 



The following is a comparison between Mr. Somerville's List of 

 1886 and the new Revised List of the Conchological Society in 

 1901, showing the progress made during the intervening years : — 



The total number of species of mollusca in 1886 \ 



was 551, ... ... ... ... ... (increase, 



The total number of species of mollusca in 1901 [ 169. 



is 720, ; 



The total number of species and varieties in 1886 \ 



was 957, ... ... ... ... ... (^ Increase, 



The total number of species and varieties in 1901 ( -01- 



is 1,158, / 



The total number of species of Brachiopoda in'i 



1886 was 7, ... ... ... ... ... (increase, 



The total number of species of Brachiopoda in f 2. 



1901 is 9 J 



