282 



GASTEROPODA. 



and have their opening long and narrow. The large 

 and massive shells of some species are used for the 

 manufacture of cameos, which are cut out of their 

 thick substance, as represented in the accompanying 

 figure (Fig. 220), The subject is worked in relievo in 

 the white portion or outer table of the shell, while the 

 inner layer, generally of a pink or reddish-brown 

 tint, is left for the background. 



The Rock-shells (Miirex) are ornamented with 

 spines, rough tubercles, or leafy, frilled, processes, 

 arranged in a regular but peculiar order. The species 

 which we have figured (Murex temiispina) is common 



Fig. 221.— thorny woodcock. 



in cabinets, and known to collectors by the name of 

 the Thorny Woodcock. 



A purple liquor, capable of producing a rich and 

 permanent dye, is known to be produced by many 

 Gasteropods; but various species of the animals in- 

 habiting these rock shells are pre-eminent for this pro- 

 perty. Accordingly we are told that they furnished 

 the first colour which mankind was enabled to hx 

 permanently on wool and linen. AYhile a certain per- 

 son, called Hercules, strolled along tlie shore with his 

 lady-love and her dog, the latter in its sport mouthed 

 a shell, which had been tossed up by the waves, and 

 had his lips coloured by the purple juice. The lady, 

 enchanted with the beauty of the colour, yearned 

 for a dress of the same j^urple, and the wish sufficed 

 to call into exercise the ingenuity of her lover, who 



