378 THE CANADIAN NATURALIST. [Vol. V. 



The Post-pliocene specimens are larger and better developed than 

 the recent, except some dredged by Mr, Whiteaves on the north 

 shore, and I would infer from this that the shell is Arctic. (See 

 Figure.) 



Cyrtodaria siliqua, Daudin. 



Fossil — Riviere-du-Loup ; Labrador (Packard) ; Greenland 

 (Moller). I have seen in the Post-pliocene of Canada, only an 

 imperfect and decorticated specimen of the young shell from 

 Riviere-du-Loup. 



Recent — Gulf of St. Lawrence, and coasts of Nova Scotia and 

 New England. 



Mactra (^Spisula) ovalis, Gould. 



M. polynema, Stimpson. 



Fossil — Boulder clay; Cape Elizabeth, Maine. 



Recent— Gaspe ; Labrador (Packard) ; also coast of New 

 England. 



I found, many years ago, a few specimens of this shell at a cove 

 where a number of species of marine shells occur in Boulder-clay, 

 and it was published in my list of shells from this place in my 

 paper on the Post-pliocene of Labrador, Maine, &c. It is credited 

 by Packard to " Zeeb's Cove," Cape Elizabeth, which may prob- 

 ably be the same place where I procured it. This species has 

 not yet been found within the limits of Canada in the Post-plio- 

 cene, though this and the related species or variety, M. solidis- 

 sima, are found living at Labrador. It has perhaps moved 

 northward since the glacial period. 



Mesodesma (^Ctronia) deaurata, Turton. 



Fossil — Matanne River (Bell.) I have not seen it in any 

 other locality ; and it occurs only on the lowest terrace, so that 

 possibly it is modern. 



Recent — Abundant at Tadousac and elsewhere in Gulf St. 

 Lawrence ; Labrador (Packard.) 



This must be a modern species on our coasts ; but according 

 to Wood it is found in the Red Cras; of E no;! and. 



Vcnericardia (^Cardita) borealis, Conrad. 



Fossil — Labrador (Packard.) 



Recent — Arctic seas to Long Island, and common throughout 

 the Gulf of St. Lawrence. It would seem to have been much 

 less generally distributed in the Post-pliocene. Western America 

 as far south as Catalina Island. (P. P. C.) 



