THE NAUTILI'S. 123 



Mr. Melvill says: I first noticed the deterioration of a Mitra 

 (ZierUanci) ziervogeliana\n our National Collection, now many years 

 ago, and a year or two afterwards the disease had spread to another 

 example on the same tablet. I have never had any specimens in 

 my own collection thus attacked, excepting one, and that I fancy 

 must have come into my possession diseased, and it was forthwith 

 destroyed. But none of these are glued or affixed in any way to 

 tablets, as is the case in most museums, but are either placed loose 

 on cotton wool, or in glass-topped boxes. I may add that I have 

 seen too frequently in the almost hermetically-sealed drawers under 

 the cases in the British Museum a dulness first pervading the exter- 

 ior of certain smooth species more markedly e. g., Conus, Cypraaa, and 

 especially Naticidae. Then grey acid efflorescence, both tasting and 

 smelling strongly of vinegar, covers the whole surface like a powder, 

 rising doubtless from the interior, and the specimens are soon almost 

 irretrievably ruined. This evil being, therefore, of most serious sig- 

 nificance, the sooner one is able to cope with it satisfactorily the 

 better, and I am sure our best thanks are due to Mr. Byne for hav- 

 ing been the first to take the matter in hand. 



From Mr. Byne's exhaustive paper we extract the following ; 



" The shells which formed the subject of my experiments were 

 from the National Collection at South Kensington, furnished me 

 through the courtesy and kindness of Mr. E. A. Smith. These alone 

 are referred to unless where otherwise distinctly stated. The shells 

 in the cabinet drawers are in many instances either partially or en- 

 tirely destroyed, the surface being corroded and covered with a fine 

 white powder substance, which can be easily scraped off with a knife. 

 This caused them to resemble Eocene mollusca. 



Many species are quite unrecognizable on account of the surface 

 being eaten away so deeply. The destruction has traveled from 

 shell to shell and drawer to drawer, like a disease, several valuable 

 specimens being spoilt. 



The mischief has assumed large proportions, and being still on the 

 increase causes the greatest anxiety. 



The most remarkable facts are 



1. Only marine species are attacked. 



2. Highly polished shells, such as those of Cyprrea, are the most 

 liable to be affected. 



3. It does not extend to every specimen in a drawer, and of sev- 

 eral mounted on the same tablet, perhaps one only is attacked. 



