TAPES. 361 



fauna ; but it is universally common southwards as far 

 as the iEgean and probably Senegal. 



The shell was well figured by Lister as English. He 

 noticed the purplish-violet stain inside, and inquired 

 whether the dye of the ancients could have been pro- 

 cured from bivalves as well as from univalves. This 

 question has never been answered by any physiologist 

 or antiquary. He also mentions that the shells are 

 called " purrs " in some parts of England ; Petiver and 

 Dale give the same provincial name. According to 

 Collard des Cherres, the Breton designation is "pa- 

 lourde," which is also applied in that province to Pec- 

 ten maximus. M. Gay informs us that it is known at 

 Toulon as " clouvisso." The animal makes a favourite 

 dish in continental seaports ; and Mr. Dennis writes 

 me word that both this and T. pullastra are eaten in 

 Sussex. It has been observed by Mr. Rich to be more 

 tenacious of life than T. pullastra. He kept some of 

 the present species alive in fresh water for eight or nine 

 days, but none of T. pullastra survived for half that 

 time. He also found the colour of the shells of both 

 these species, when put into hot water or near a fire, to 

 change from dark purplish-brown to a brick-red hue. 

 Montagu justly remarked that the siphons differ from 

 those of T, pullastra in being divided to their origin ; 

 but he was mistaken in supposing that both tubes were 

 protruded in search of food. Mr. Clark says, " This 

 species is much more common than the P. pullastra ; 

 they live together in the same shingles, and have pre- 

 cisely the same habitudes; notwithstanding this com- 

 munity they are very distinct." His opinion on the 

 last point is the more valuable because he was by no 

 means a species-maker. The young of T, decussatus are 

 nearly square, while those of T. pullastra are oblong. 



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