34 MEMOIR OF 



ceals itself in the dog-days. It lives generally seven 

 years, and. can exist for fifty days out of the water. 

 The circles of its shells correspond to the years of 

 its existence. In Carteia it has been found weigh- 

 ing ten pounds. It is killed by rain and fresh 

 water. Aristotle describes the method by which it 

 is caught with the net ; its flesh is hard. Dios- 

 corides and Galen dwell upon the diseases in which 

 it is useful ; there are several species, the best of 

 which is that of Tyre." 



Once more, with regard to a true conchifera, the 

 pecten or scallop-shell (Pecten, Lamarck), Salviani 

 tells us its common appellation is St. James' shell, 

 from the custom of pilgrims wearing it in their 

 hats or about their neck, expressive of their 

 crossing the sea in their way to the Holy Land, 

 or to some distant object of devotion. The 

 pecten is a shell-fish and a bivalve ; the shell is 

 striated, whence its name. One of the valves is 

 swelling, the other flat ; each shell has two pro- 

 jecting auricles. It has an ovum on one side of its 

 edge, which nearly disappears during spring; for 

 as the season advances the ovum diminishes in 

 size, till at length it quite disappears. It is 

 produced spontaneously, in sandy places, and in 

 spring. It grows rapidly, for it attains its full size 

 in a year. On moving the finger towards it, it 

 gapes, and immediately closes its shell, as if it 

 noticed and observed. It springs about, and is 

 observed to make a noise when it moves ; it con- 

 ceals itself in great heats and colds ; it is injured 



