THE ECONOMIC USES OF SHELLS. 469 



this work and have not been able to obtain a specimen. Information regarding 

 it, the species of shell employed, and whence obtained, would be interesting. 



Another ornamental use to which shells are put is the carving of Cameos, 

 which it is hardly necessary to describe as engraved gems in which the subject 

 is cut in relief. For the best cameos stratified stones, such as onyx and agate, 

 are used, but owing to the difficulty of obtaining suitable material shell 

 cameos were introduced in Italy about the fifteenth century. The most useful 

 shells are of course those with several layers of different colours, and I find the 

 " Bull's mouth " with the under layer red, the " Black helmet" with a dark onyx 

 ground, and the " Queen's conch" with a pinkish ground described as the most 

 valuable for the purpose, but I have not been able to ascertain the genera to 

 which these shells belong. 



Before leaving the subject of the uses of shells for ornamental purposes I 

 must here mention the Giant Clam (Tridac?ia gigas), which have been known 

 to weigh as much as 500 lbs. the pair, as used for containing holy water in 

 French churches — notably a pair at St. Sulpice in Paris. I must also draw 

 attention to the many highly artistic and ornamental articles made from shells 

 that have been loaned to us for the occasion by Bhicaji & Co. — most of which, 

 I am informed, are manufactured in Siam — and the panels of Japanese work 

 inlaid with carved shell lent by Hinode & Co. 



Our next consideration must be the uses to which shell-fish are put as an 

 article of food. This is a subject that might well be made into a paper by itself, 

 as the use of them is universal all over the marine littoral of the world. 



First and foremost of course from a European point of view come the edible 

 oysters, which are regarded as a delicacy wherever Europeans are found. 



According to Messrs. Melville and Abercrombie's paper that appeared in our 

 Journal, Vol. VIII, p. 345, the edible oysters of this coast are stated to be 

 probably confined to two species, viz., Ostrcea plicata (or crenulifera) and 0. 

 bicolor, but it is admitted that the discrimination of the species is very difficult. 



Regarding the use of them by natives on this coast Mr. Aitken writes that 

 "from Bombay southwards the oyster is eaten by the Hindu fishermen and 

 lower castes. In Sind, where the poorer population is Mahomedan, the oyster 

 is not eaten, nor any other molluscs I believe. Karachi was once famous for 

 its oysters, but now the demand is mostly supplied from Kathiawar and Cutch. 

 During the last few years efforts have been made to protect them by closing 

 certain sections of the coast for a time and forbidding the removal of shells 

 under a certain size." 



While on the subject of edible oysters some reference is necessary to the 

 artificial cultivation of them. As many as 2,000 years ago this appears to have 

 been undertaken on a large scale by the Romans, who appreciated oysters as 

 much as we do at the present day, and oyster farms have been more or less 

 paying concerns ever since. The most extensive on the British coasts are those 

 at Whitstable on the Thames estuary, where they extend over an area of more 

 than 27 square miles; but, large as these and other British oyster farms may 



