27 



Shell Life 



Canoe-shell 



The Canoe-shell {Scaphander lignarius) is a many- 

 whorlecl spiral of reddish hue, whose lines and grooves 

 give it some resemblance to the 

 grain of fir-wood. The yellowish 

 animal has a large shield - shaped 

 head, and the tentacles are united 

 to form a squarish lobe behind it. 

 The eyes are not developed owing 

 to the fact that this mollusk burrows 

 in the sand for its food. It per- 

 sistently hunts the little Tusk-shell 

 (Dentalium entale), crushing the 

 shell in its powerful gizzard and 

 digesting its contents. Jeffreys says it "does not 

 despise any kind of animal food, from minute 

 Foraminifera to the Sea-mouse or Aphrodita, the 

 spines of which I found in the gizzard of one 

 individual. Corhula gihha is evidently a favourite 

 morsel; and I have observed Bentaliiini entcdis, 

 Odostomia rufa, and Bitrupa arietina in other 

 specimens." It occurs generally in the coralline zone 

 in from 50 to 90 fathoms. Another species, Sca'ph- 

 ander punctostriatiis, occurs at Shetland and the 

 Butt of Lewis in deep water. 



The Cylindrical Bubble-shell {Cylichna cylin- 

 dracea) is distinctly cylindrical, with blunt ends, and 

 about 1 inch in length, 

 though the animal is much 

 longer. Both animal and 

 shell are white, but the latter 

 has a dark yellow epidermis. 



It presents a singular appearance with its flattened 

 head and flap, consisting of the united tentacles, ex- 



Cylindrical Bubble-shell 



