282 BUCCINID^. 



and Dutch, each contributing something to our know- 

 ledge. Professor Lacaze-Duthiers has lately given an 

 excellent resume. From all these publications and my 

 own observations I may state that the dye-stuflp, when 

 extracted from the living animal, is of the consistency 

 of cream, and at first colourless or more or less yellowish ; 

 exposed, in a moist state, to the light of the sun, it 

 passes through all the different shades of green to violet, 

 then to a beautiful purple, and ultimately becomes 

 crimson ; the colour is photogenic or produced by solar 

 action. A smell of garlic is given out during the pro- 

 cess. Linen was formerly stained or marked with it. 

 The liquor contained in the egg-capsules is also purpu- 

 riferous, and tastes like the strongest pepper. P. A«- 

 mastoma ^Y^^Murex erinaceus possess the same colouring- 

 matter. When amusing himself by some experiments 

 as to the faculty of hearing possessed by the mollusca, 

 Dr. Johnston ascertained that neither this kind of whelk, 

 the periwinkle, nor the common banded snail appeared 

 to be affected by loud and harsh noises about them. 

 M. Susini, however, informs me that at Corsica Trochus 

 tesseUatus or T, fragaridides (which is there gathered 

 by the fishermen, and after being scalded eaten with a 

 pin, like our periwinkle) invariably drops down from 

 the rock when any one approaches it. The shell of 

 the male P. lapillus is longer, more slender, and has a 

 finely tapering spire, with a plicated but not tubercular 

 throat. Specimens from brackish water in the Solent 

 and River Orwell are smaller and of a thinner texture. 

 In one from Guernsey there is a strong fold on the 

 upper part of the pillar, exteading inwards. Occasionally 

 the shell is truncated at the top, or the first whorls are 

 broken and deserted, the animal occupying the re- 

 mainder. In aged specimens the throat has not unfre- 



