418 mactrid^:. 



south of Sweden (Loven), at depths of from 7 to 150 

 fathoms. 



M. solida was formerly, and perhaps is still, eaten in 

 Devon and Cornwall. In Leigh's ( History of Lan- 

 cashire ' it bears the singular and certainly not plebeian 

 name of " a pectnncnlus with azurine circular lines in- 

 terpolated." The animal is not in the least timid ; and 

 soon after being caught and put into a vessel of sea- 

 water, it displays its agility by leaping about with its 

 tubes extended. In some specimens of the variety 

 elliptica the lateral teeth in the left valve are only 

 striated on the outside. The authors of the ' British 

 Mollusca ' owned, in the Supplement to that excellent 

 work, their suspicions that the M. truncata of Montagu 

 ought to be united with the present species. I must 

 take another step in the same direction, and reduce 

 the M. elliptica of Brown to the rank of a variety. I 

 may be wrong, and am open to conviction ; but I con- 

 fess that I cannot draw a line which will separate one 

 more than the other of these so-called species from the 

 typical form. I expect that some of my scientific 

 readers will lay down the book and say to themselves, 

 " Well ! I wonder where all this radical innovation will 

 end ! Who can possibly doubt M. elliptica being a good 

 species ? Why, it is much smaller, of an oblong shape, 

 thin, and glossy ; while M. solida is triangular, thick, 

 and dull. Even the young of each species exhibits 

 its peculiar characteristics." In reply I would ask the 

 annotators to recollect the much greater difference that 

 exists between shells of Buccinum undatum taken at 

 low water and at a depth of from 70 to 80 fathoms, as 

 well as with respect to Venus gallina and other bivalves 

 subject to similar bathymetrical and climatal changes. 

 I regard M. truncata as the littoral or shallow-water 



