78 SCOTT : LAND AND FRESHWATER MOLLUSCA OF TARBERT. 



Cochlicopa lubrica (Miill.). Generally distributed. 



C. lubrica var. densata Baudon. ' White Shore,' East Loch 



Tarbert. rare. 

 Carychium minimum Miill. Generally distributed. 



In concluding this paper, I wish to draw attention to a 

 difference I have observed in the habits of Helix arbustorum 

 and H. aspersa and H. nemoralis. When hunting for snails, if 

 the evening is mild and dry I am sure of getting H. arbustonwt 

 in the localities where it occurs, marching about quite freely ; 

 H. aspersa will also be found fairly plentiful, but H. nejiioralis 

 is rarely met with ; but should there be a mild rain, however, 

 then H. nemoralis may be seen almost everywhere within the 

 area where it is found, the same with H. aspersa, but very few 

 specimens of H. arbustoi'um are to be seen. Within the limit 

 of the castle ruins I get H. ne??ioralis of a uniform yellow 

 colour, the shell rather thin ; of a yellow colour with one dark 

 band (the most common variety) — from that to specimens having 

 five dark bands; and, lastly, specimens almost black and rather 

 solid. Among the specimens of this species I have noticed, 

 is one where the mollusc has evidently formed its shell of a 

 uniform yellow colour till near maturity, when it seems to have 

 acquired gradually the power of secreting pigment to form a 

 dark band. About one-and-a-half-inches back from the lip 

 where the band begins, there is the merest streak of colour, 

 which progresses in an intermittent manner for some distance, 

 when it gradually becomes more decided till where it term- 

 inates near the lip the dark colour is of the usual breadth and 

 density of the band seen in the one-banded variety — i.e., 00300. 

 The question, how does the mollusc acquire the power wheri 

 near, or at maturity, of depositing a pigment of a different 

 colour in its shell, may not be easily answered, but that power, 

 though seldom exhibited as in the case described, is evidenced 

 in unicoloured yellow or reddish shells having black lips. 



J.C, v., July, ISS6. 



