88 



J^OTES ON THE EFFECTS OF THE ATMOSPHERE 

 ON THE SHELLS OF MOLLUSCA. 



By Mrs. Agnes Kenton. 

 Bead May 2Sth, 1896. 



I think it is well for the benefit of conchologists to put 

 down some observations on this point. I have frequently 

 noticed the fading of colour so observable in some specimens. 

 I have some Cyprea which some years ago were found alive at 

 Portland, Yic, crawling over the rocks there, at one time so 

 abundant. Such specimens as I still have are now of a light 

 grey colour, which when first procured were so dark as to be 

 almost black. This I had attributed, along with most others 

 with whom I had any conversation on the subject, to the 

 effects of the sunlight ; however, this in my experience has 

 proved to be an error, as it is the results are evidently due to 

 the atmosphere and not the light, as heretofore supposed. 

 While on a visit to Tasmania I had the opportunity of visit- 

 ing a collection on which the near vicinity of the sea had the 

 effect of partially destroying the enamel of the dorsal 

 surface, by streaks or clouds of a whitish or lime-like sub- 

 stance, the saline particles held in solution in the atmosphere 

 evidently exerting a corroding effect in this instance ; though 

 on my return from my four weeks' stay in Tasmania I had 

 an unexpected instance of a still stranger effect brought 

 under my notice. I have had in my possession for the last 

 six or seven years a matchless specimen of a young Orange 

 Cowrie {Cy. aurantium) of a lovely deep orange red colour ; 

 unfortunately before leaving home I had happened to remove 

 it to the lowest drawer in a cabinet placed next the outer 

 wall of the dining-room. The cabinet had a plinth about 

 2in. high, having a wooden bottom, and the drawer had also 

 a wooden bottom lined with domestic cotton. The shell, 

 being a young shell and very thin, was for greater security 

 placed in a glass-topped box, and the doors of the cabinet 

 were not unlocked during my absence, yet on my return, 

 owing to some excessive rains having engendered dampness, 

 the beautiful red colour (so rare) had all faded out, leaving 

 only a small patch in the centre of the dorsal surface. The 

 polished enamel is still perfect, and is in all other respects 

 the same but the fading of the colour. 



