1 68 OYSTERS, AND ALL ABOUT THEM. 



The hooded crow is very fond of these scallops. It 

 takes one from the tangle at low water, and carries it to 

 the shore or a bank, on which it drops its prey, watching 

 with cunning patience until the scallop opens its shell. It 

 then quickly thrusts its pointed and strong beak into the 

 gaping valves, forces them asunder, and devours the dainty 

 morsel. Dead and bleached shells are thus often found in 

 places at some distance from the sea, where crows had 

 been feasting. Without this explanation they might have 

 been mistaken for fossils. 



The only points of difference between P. varius and 

 P. nivetis consist in the latter having a broader and flatter 

 shell, with more numerous and delicate ribs, and in the 

 colour being white. ..... 



The strong and few-ribbed P. varius lives on oyster-banks 

 and rough ground, on an exposed coast ; while the delicate 

 and many -ribbed P. niveus is only found in sheltered lochs 

 and arms of the sea, moored by its strong byssus to the 

 upper surface of the broad and smooth fronds of Lamin- 



t ( / L (. i. 



Dr. Gray, in commenting on the species in question (Ann. 

 Phil., No. 59, p. 387), says: " Macgillivray only compares 

 it with P. varius, perhaps not aware that Pecten Islandicus, 

 Lam., of which this shell appears to be only a variety, has 

 long been known "as a British species." The last-named 

 species, however, has never been found in Great Britain 

 except as an upper tertiary fossil, and it has only a generic 

 resemblance to Macgillivray's shell. 



P. Islandicus. F. Gulf of Naples, in 50 f. ; a single 

 valve in a semi-fossil state, like those dredged in Shetland, 

 and covered with the same arctic species of Spirorbis ; with 



