THE DIATOMACE OF THE HULL DISTRICT. 161 
as Coscinodiscus oculus tridis of the Arctic Ocean becomes C. 
concinnus of the North Sea. 
Norman’s first list comprised about 400 species, and was 
then the longest local list that had ever been published. The 
revised edition of 1865 contained about 480 species. The 
present list comprises about 600 species and varieties, and we 
think it is worthy of notice that this is about one half of the 
species known to be inhabitants of Great Britain and Ireland. 
Notwithstanding this we do not regard the list as anything 
like complete, but feel sure that with further research many 
species hitherto unrecorded will be found, and we should wel- 
come communications from observers who have obtained 
such forms. These will be inserted in future issues of the 
Club’s Transactions. 
[For the very excellent drawings of diatoms on the 
accompanying plates, as well as the plates themselves, the 
Club is greatly indebted to Mr. Mills.—Ed. ] 
