HALF AN HOUR WITH SHELL-FISH (BIVALVES). 219 



Fig. 119. 



by melted snow or ice, as that of the north frequently 

 is. It is not so brilliantly coloured as the species 

 we have just mentioned, but has the same generally 

 diffused pink hue. 



Donax is a bivalve nearly allied to the former. 

 One species (anatinus) is very abun- 

 dant with us. The animal which 

 forms the shell has a stout yellow 

 foot, and a frilled mantle. When 

 the empty shell is examined along 

 its inner margin, the latter is seen 

 to be milled, like the edge of a 

 new shilling. When alive, or when the empty shells 

 have been cast ashore shortly after death, the colour 

 is a pale olive, which is that of the investing mem- 

 Fig. 120. 



Tettina Balthica. 



Donax politus. 



brane. In old and dead shells, when this is removed, 

 the colour is white, with light purple shadings. Donax 

 politus (Fig. 120) may be distinguished from the fore- 

 going by the white bands which radiate from the beak. 



