182 BIOLOGICAL SURVEY OF 



A. SIMPLEX d'Orbigny. (d'Orbigny, 1845, Moll. Cubana; 

 A. ephipphmi Gould, 1870, Inv. Mass., p. 204, fig. 497.) Com- 

 mon with the preceding form and distinguished from it by 

 lack of scales on the surface. Common Maine to Connecticut ; 

 southern coast of Nova Scotia, off Cape Sable, 8 fathoms. 



Mytilidae 

 Mytilus Linne 



M. EDULis (Linne). (Linne, 1758, Syst. Nat.; Gould, 1870, 

 Inv. Mass., p. 183, fig. 483.) The common mussel of commerce, 

 and occurs in great abundance in this Region, adhering to 

 piles, rocks, etc., and forming vast beds on the mud flats. 

 Serve as bait for fishermen. Their growth interferes seri- 

 ously with channels through the flats. Common on the 

 Canadian and Labrador shores. Is circumpolar and also a 

 Pleistocene fossil in Canada. 



M. EDULIS PELLUCiDus (Penuaut). Pennant, 1777, Brit. 

 Zool. ; M. edulis var. pellucidus Gould, 1870, Inv. Mass., p. 184, 

 fig. 484.) While not so common as the preceding form, it 

 occurs with it in great quantities. Very inconstant as to ra- 

 diations and shading. 



Modiolus Lamarck 

 M. MODIOLUS (Linne). {Mytilus modiolus Linne; M. modi- 

 olus Lamarck, 1799, Nouv. Class. Coq. ; M. modiolus Gould, 

 1870, Inv. Mass., p. 186, fig. 485.) This inhabitant of deep 

 water is often cast upon the shore after storms attached to 

 Laminaria. Common and known as the 'horse mussel.' Speci- 

 mens taken nearly 6 inches in length. Sometimes found in 

 tide pools at spring tides. Hard and shell bottoms. Stations : 

 D 53, 135 ; S 14, 21. Some large ones in tide pools on outer 

 side of Long Porcupine. Common from Maine to Connecticut, 

 from low water to 80 fathoms. Common, circumpolar, and a 

 Canadian fossil form, though rare. 



