149 

 Saxicava rugosa (L.). 



Miia arctica, L. (1767). Syst. Nat., ed, xii., vol. i., pt. 2, p. 1113. 



Solen minutus. L. (17G7). Op. cit., p. 1115. 



MytUus rugosus, L. (1767). Op. cit., p. 1156. 



Mytilus pholadis, L. (1771). 



Mya arctica, O. Fabricius (1780). 



Mya hyssifera, O. Fabricius (1780). 



Saxicava rugosa, Lamarck (1818) ; et aiict. 



.'' Saxicava distorta. Say (1822). 



Both Verrill and Dall include S. rugosa among the synonyms of S. arctica, 

 and it now seems to be generally conceded that there is but one species of 

 Saxicava in the north Atlantic and Pacific. The name Mya arctica seems 

 to have been gi^en by Linnseus to young or half-grown shells, or specimens 

 of a small variety, with well defined lonule and posterior area, the latter 

 usually marked with two spinose longitudinal ridges in each valve ; and that 

 of Mytilus rugosus to large, adult individuals of the same species, with the 

 lunule and posterior area obsolete. As the Rev. G. W. Taylor has said : — 

 ^^ arctica is the earliest specific name for this shell, but it was applied by 

 Linne to a variety, while the name rugosus was given to the typical rock- 

 boring form. Pholadis, a still later name, was given to another variety " . . . 



"that has the shell gaping widely in front and to which Jefi^reys 



(Brit. Conch., vol. in., p. 82) restricts the na.me pholadis."* 



S. rugosa (including 6'. arctica) is equally common in the north Atlantic 

 and north Pacific. On the western side of the Atlantic it is known to range 

 from Long Island Sound (and perhaps from Georgia and South Carolina) to 

 Greenland and the Arctic Ocean ; and, in depth, from low-water mark to 50 

 fathoms or more. Shells of this species, as stated by Dall, are found 

 " burrowing, or nestling in gravel or broken shells, or perforating rocks, 

 corallines, or dead shells, like pholads," and often with them. When not 

 boring they are attached by a byssus, and in Casco Bay, in 10 to 15 fathoms, 

 Verrill says that he has found specimens " perforating recent and sound 

 shells of Cyprina Islandica." 



The species is widely distributed throughout the whole of the reniou now 

 under consideration, except perhaps in the very deepest parts of the Gulf of 

 St. Lawrence, where the bottom does not seem to suit it, and northward to 

 the Atlantic coast of Labrador, Hudson Strait and Bay. In Hudson Strait, 

 living specimens have been dredged at Ashe Inlet by Bell in 1884 ; and 

 between King George Sound and the bottom of Ungava Bay by Low in 

 1897. On the west coast of Hudson Bay similar specimens have been 

 dredged twenty miles c^T Fort Churchill, in 30 fathoms, by Commander 

 Wakeham in 1897 ; and on the east coast of Hudson Bay, by Mr. Low, near 

 the mouth of Povungnituk lliver in 1898 ; and in Richmond Gulf, in 1899. 



* Transactions of the Royal Society of Canada for 1895, Second Series, vol i. , sect. n'. 

 p. .o.S. 



