144 OYSTERS, AND ALL ABOUT THEM. 



range also comprises Algeria, Madeira, North America, 

 Russia, Lapland, and the Black Sea. Danielssen has 

 recorded it as having been dredged in the Scandinavian 

 seas at a depth of 180 fathoms. 



In consequence of the lower valve being moulded on 

 the extraneous bodies to which it is attached by the plug, 

 the upper valve partakes of a corresponding impression, 

 and the result is that the shell puts on a Protean variety of 

 shape. Bouchard-Chantereaux says that out of two hun- 

 dred specimens it is almost impossible to find two exactly 

 alike. 



When a specimen is affixed to a Pecten, As/arte, or 

 other ribbed shell, it is similarly sculptured. No less than 

 thirty-four species have been made out of the one now 

 described, and naturalists of every country have had a hand 

 in this wholesale manufacture. Eighteen of these species 

 have been enumerated as synonymous by Forbes and Hanley. 

 The variability of the shell, however, is now such an estab- 

 lished fact, that a conchologist who would attempt to restore 

 any of these so-called species must have greater ingenuity 

 than even the learned knight, of whom it was said 



" He could distinguish and divide 



A hair, 'twixt south and south-west side." 



The variety " squamula ' is flatter and smoother than 

 usual; " aculeata " has the imbricated scales pinched up 

 into vaulted or hollow spines ; and the narrow form of 

 "cylindrica'*' arises from the young Anomia selecting for 

 its resting-place a small stem of sea-weed, which obliges it 

 to assume a saddle-shape, not having any room for lateral 

 development. Occasionally specimens are found exhibiting 

 the characters of more than one variety, being half " squa- 

 ^ and half "aculeata" The animal is said to be 



