i88 



Shell Life 



dHy^ 



backwards into a spiral. Within it has a triangular 

 shelf-like plate, occupying half of the crown. It is a 

 deep-water (18 to 100 fathoms) species, plentiful on 

 nullipores around Ireland, Scotland, and Shetland. 



The Common Limpet {Patella vidgata). So 

 generally common and well-known a species is in 

 need of no description, beyond saying that the shell 

 is conical and solid, with ribs radiating from the 

 beak. It is variable in colour, some young specimens 

 being olive-grey, others more yellowish with purple 

 rays. As it gets older the beak gets completely worn 

 away, the ribs rubbed down, and 

 possibly the whole surface made 

 smooth and almost even. Other old 

 specimens get covered with nullipore, 

 or support a forest of delicate weeds. 

 The inside is very glossy, being coated 

 with nacre, which exhibits greenish 

 opalescent gleams. Through this 

 layer the purple rays may be seen 

 more or less clearly, though all trace 

 of them may have gone from the outside. In the 

 centre there is a large white patch showing the 

 attachment of the muscle ; it is in the shape of a 

 broad-mouthed amphora. A less distinct depression 

 around it marks the attachment of the mantle. The 

 general appearance of the Limpet from beneath 

 when detached from the rock is shown in the cut. In 

 the centre is the broad muscular "foot" by which 

 adhesion to the rock is effected ; in front of it the 

 distinct head, with mouth, paired tentacles, and eyes ; 

 around the whole is the frino;ed mantle, and between 

 the mantle and the foot there extends a frill of gill- 



Common Limpet 



