356 The Commercial Products of the Sea. 



another for the internal surface. When a sufficient quantity 

 of small particles of shell is put into the lower mould, 

 which is to form the external surface, the upper mould is 

 placed upon them, and gently pressed down by a screw 

 attached to a frame which contains both moulds. The 

 frame and moulds are then immersed in boiling water, and 

 as the particles of shell become softened, the screw is 

 gradually turned, so that the shell becomes pressed into a 

 soft continuous film, occupying the whole of the space 

 between the two moulds. The moulds are then allowed to 

 cool, and the shell is removed from between them, when it 

 is found to give accurate representations, in relief, of any 

 objects which may be engraved on the moulds. This mode 

 of manufacture has been carried to great perfection in 

 France, from whence snuff-boxes in great variety are pro- 

 cured. The French have also made hollow walking-sticks 

 of pure tortoiseshell, by joining strips of shell together, and 

 moulding them round a central stick or core, which is 

 afterwards removed. 



The scales of the plastron, or under-shield, are of a 

 yellow colour, and are used for many of the purposes of 

 horn. This shell differs entirely in appearance, for instead 

 of the mottled shaded colour with its varying tints and 

 markings, it is of a bright yellow, resembling somewhat the 

 " hoof," or connecting marginal pieces ; but as these ap- 

 proach the upper part of the shell, they partake of its 

 mottled colouring. 



The under plates and hoof are used for the manufac- 

 ture of the gold or amber-coloured semi-transparent combs 

 so much admired abroad. The Spanish ladies will often 

 give .3 or 4 for a comb of plain yellow tortoiseshell, 

 while a similar one of the mottled kind would not fetch 

 there, perhaps, more than 2Os. or $os. Such is the influence 



