148 



the foim described by Stimpson as Necera pellucida is quite distinct from 

 that described by Loven as N. obesa, with which it has been so long 

 confounded,"* 



Family Myidce. 

 Mya arenaria, L. 



Common almost everywhere in the Maritime Provinces and Gulf of St. 

 Lawrence, the known geographical range of the species on the western side 

 of the Atlantic being from South Carolina to the Arctic Ocean. Adult 

 shells are usually found living at or near low-water mark, but young 

 specimens, as Professor Verrill observes, are occasionally dredged in as deep 

 water as 40 fathoms. Sir J. W. Dawson says that he has a specimen five 

 inches long from Gaspd 



The shell, which is circumpolar, occurs fossil in the Red Crag and later 

 formations of Great Britain ; in the Miocene of Virginia ; in the Leda clay 

 and lower part of the Saxicava sand, of Maine, New Brunswick, Quebec and 

 eastern Ontario ; and in the Pleistocene of Greenland and Europe. 



Mya truncata, li. 



Widely distributed on both sides of the north Atlantic and known to 

 range from Cape Cod to the Arctic Ocean, but not nearly so common as M. 

 arenaria in the Gulf of St. Lawi-ence, and usually found in deeper water. On 

 the Le Have Bank, near Cape Sable, N.S., specimens of it were dredged in 

 45 fathoms, by the U. S. Fish Commission in 1872 (Smith and Harger). The 

 comparatively long and typical form of M. truncata seems to be the more 

 common of the two in the lower St. Lawrence and southward, and the short 

 and abruptly truncated form, the var. Uddevallensis, northwai'd. Packard 

 dredged specimens of the latter near Caribou Island in 1861 ; and in 30 

 fathoms, abundantly, off Square Island, Labrador, in 1864. All the specimens 

 oi M. truncata collected by Bell at Ashe Inlet and Port Burwell in 1884 

 are referable to the var. Uddevallensis. In (Greenland both M. arenaria and 

 M. truncata are said to be common at low-water and are eaten (as is also- 

 Mytilus edulis) by the walrus, Arctic fox, Esquimaux dog, raven, and eider. 



The species has been recorded by Sir J. W. Dawson as having been col- 

 ected in the Saxicava sand and Leda clay, at Portland, Maine ; New Bruns- 

 wick ; New Richmond, Anticosti, Riviere du Loup, Riviere des Outardes, 

 Quebec, and Montreal, P.Q. ; and Labrador- also in the Pleistocene deposits 

 of Greenland and northern Europe. In eastern Canada it is much more 

 abundant as a post-tertiary fossil than as a recent shell. 



* Proceedings of the U. S. National Museum, vol. xx., p. 804. 



