1 62 Shell Life 



roots of the larger seaweeds. The shell is more 

 angular, the wrinkles become ridges, and the teeth 

 are more evident. Its specific distinction 

 from >S^. riKjosa is very doubtful. 



Norwegian Rock-borer (/S^. norvegicci). A 

 much larger species, attaining the dimensions 

 of 3 inches by 2, has been found in deep water (30 

 fathoms) between the Dogger Bank and the east coast 

 of England, where it bores into thick mud. The out- 

 line of the shell is an irregular oval, the right valve 

 larger than the left. It gapes at both ends, and is 

 similar in colour, texture, and ornamentation to its 

 smaller relative. The teeth are similar to those of 

 the foregoing. The siphons are protected by a dark 

 leathery sheath, and the lower tube is larger than the 

 upper one. From its restricted area in British waters, 

 and the difficulty of obtaining specimens, it is one 

 of the most highly priced of native shells in the 

 catalogues of the dealers, a good example costing 

 a sovereign. 



The Flask -shell {Gastroclimna duhia) bears some 

 resemblance to a young mussel when viewed from 

 above ; but below, towards the 

 foremost end, there is an enormous 

 oval gape as shown in our figures. 

 It is very variable, smooth, of the 

 whitish grey so frequent in the 

 shells of borers, but covered with 

 a yellow-brown epidermis. There Front view 

 is a broad thin hinge-plate, but 

 no teeth in either valve. The 

 animal is pale reddish brown, with the mantle lobes 

 united below and having only sufficient aperture to 



Flask-shell 



