SECTION XIII. • 275 



Cockles, but on the longeft fide, from 

 the beak to near the extreme margin, the 

 two Shells do not clofe, but leave a large 

 oval or heart-like gap or opening, the lips 

 whereof are very broad, and turn up on 

 the edges. PI. VII. fig. 4^ 5 *. 



Thefe are the Bafon Conques, &c. of 

 which there are few fpecies : but they are 



the largeft and heaviefl: Bivalves yet known, 

 fome weighing from three hundred and 

 a half to fix or {tven hundred weight. 



(lenus 2. Chami^, Purrs or Gapers. . 

 The Chamas have a broad, thick, and 

 large tooth for their hinge, and are, as 

 it were, abruptly cut off on one fide, which 

 fide is always open or gaping, as the valves 



* T think fome diflinclion flioiild be made between 

 thefe and the Chamae. The Apertures in the firll are 

 meerly to tranfmit a fae tentaculum^ to prevent their 

 being dafhed to pieces by the rocks and waves. The 

 Hiatus in the Chamai is for a very different purpofe, 

 to permit the fifh to extend itfelf in fearch of food, 

 and immediately to retire in cafes of danger. 



T 2 cannot 



