BUCCINUM WHELK 89 



dinally, and transversely crossed with finer irre- 

 gular striae ; apex small, pointed ; aperture oval ; 

 outer lip waved or denticulated ; it is usually of 

 an uniform dirty white, or yellowish colour, 

 sometimes banded with brown or yellow. Length 

 rarely exceeds two inches, breadth one. 



The animal that inhabits this shell has two 

 slender tentacula-bearing eyes about half way 

 up on the outside, the ends of the tentacula as far 

 ,as the eyes are retractile* like those of snails. 

 Its mantle forms a tube through which it breathes : 

 it has a foot with a horny operculum. Near to 

 its head, and lying in a little furrow, is a white 

 vein which yields a beautiful purple tint, sup- 

 posed to be that so long celebrated as the Tyrian 

 rfye. In order to obtain this colour, the vein is 

 laid open with a needle, and is found to contain 

 a tenacious yellow matter like cream. As soon 

 as this fluid is put on any substance, as silk, 

 linen, &c. and exposed to the air, the yellow 

 assumes a brighter hue, speedily turns to pale 

 green, gradually becoming darker, until it has 

 obtained a blue cast, and from that it changes to 

 a purplish red, more or less deep, according to 

 the quantity used. The succession of the tints 

 is accelerated by exposure to the rays of the sun. 

 The stain given by this animal fluid, seems to be 

 indelible, bidding defiance to chemical process, 

 and it might therefore be most advantageously 

 used as a kind of marking ink. 



The Buccinum Lapillus is one of the most 



* Retractile, capable of being drawn back, from the Latin re 

 back, and tract us drawn. 



8* 



