240 THE WORLD OF THE SEA. 
minutes an extremely fetid odour was disengaged, the matter first 
becoming yellow, then green, and finally a bright purple. 
The gasteropods which furnished the purple for the Greeks 
and Romans were members of either of the tribes of Purpura or 
THE BLOODY-MOUTHED PURPURA. 
(Purpura hemastoma.) 
Murex. Of the former tribe, the Purpura hemastoma, of which 
we have given an engraving, is very prominent for its colouring 
power; but it is more than probable that every member of the 
MUREX BRANDARIS. 
species has this property. The Murex, or the rock-shells, are 
remarkable also for their bright colours and their fantastic forms. 
They are natives of all seas, but are best developed in the warmer 
latitudes, At Pompeii, some cups made of this shell were found 
