SEA-SHELLS ON THE SEASHORE 145 



You will not find the oyster there on our own coast, but 

 in Australia they have picnic parties where every guest 

 provides himself with a hammer and a bottle of vinegar 

 and a pepper-pot, and at low tide proceeds to chip the 

 oysters off the rocks on which they grow tightly fixed, 

 and to eat them " right away " before they have time to 

 lose their good temper and sweetness ! In Jamaica they 

 show you oysters apparently growing on trees high up 

 in the air, but they are dead, having attached themselves 

 to the branches of a young tree which dipped into the 

 water. Once fixed there, they were unable to move as 

 the tree grew and carried them up with its branches 

 above the sea-level. 



The only bivalve at all common and visible to the 

 eye between tide-marks is the common or edible sea- 

 mussel, which is attached in purple clusters to the rocks 

 (as in North Cornwall), or forms a wide-spreading pave- 

 ment, called a " scalp," of as much as an acre in extent, 

 on which thousands of mussels lie side by side. But by 

 digging in the sand and mud between tides there are 

 other living bivalves to be found, which burrow more or 

 less deeply. The razor-shell (Fig. 19, b) is one of these 

 (see p. 80). Often (as at Teignmouth and Barmouth) 

 we find "cockles" buried in the sand, and those delicate, 

 smooth bivalves not an inch long, white outside and 

 purple within, which are made into soup at Naples and 

 are called " vongoli," but have no English name. Other 

 " clams " (Tapes, which is eaten in France, even in Paris, 

 and Mya, and Scrobicularia which lives in black mud) 

 may be dug up, but they are devoid of English names 

 because we do not eat them ; hence I have to speak of 

 them by their Latin scientific names. As to univalves, 

 there are three which are found almost everywhere on 

 our coasts where there are rocks, namely, the periwinkles 

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