examine the very young stages of P. maximus, but P. 

 o-percularis and P. irradinns of tlie American coast have a 

 period before the free stage is reached, when they attach 

 themselves by means of a byssus. 



In a still earlier stage after the free-swimming larva 

 has settled down, the animals are unattached and crawl 

 about actively. The foot is protruded, attached to some 

 object and then contracted, and in this way the animal 

 is pulled along by successive attachments and contractions 

 of the foot. The foot of the adult Pecten is very like a 

 sucker, though in no case have I seen it used in the 

 manner above described. 



Following the crawling stage we have the byssus 

 stage, and the foot takes part in the attachment of the 

 threads. 



Jackson (3), who has watched the American species, 

 describes it as follows: — " Lying on the right valve, the 

 foot is extended on the surface of the dish, the flattened 

 distal portion taking a firm hold as if about to crawl. 

 This position is maintained for a moment or two and then 

 the foot is withdrawn within the body, by the motion of 

 retraction it draws out, or spins, the byssal thread, which 

 the creature had fixed to the surface of the dish while the 

 foot wag laid closely against it. Soon the foot is again 

 extended, pressed flatly against the dish and another 

 byssal thread is spun, three is the common number with 

 specimens in confinement." 



If disturbed the attached scallop can break or 

 cast off its byssal threads and swim by clapping its shell. 

 The adult P. ofevcularu only occasionally shows any signs 

 of the byssus, but P. varius, another common British 

 species, is usually attached. 



Pecten feeds largely on vegetable matter, such as 

 diatoms, fragments and spores of algae, together with the 



