384 THE CANADIAN NATURALIST. [Vol. vi. 



tenuisulcata, Gould, and Jacksonii, Gould. Slender and flat- 

 tened varieties are pernula and tenuisulcata, shorter and more 

 tumid forms are huccata ; and specimens decorticated so as to 

 show the origin of the hinge teeth are Portlandica . Comparison 

 of specimens from Greenland, Norway, Labrador, the Gulf St. 

 Lawrence, and New England, confirms this conclusion. (See 

 Figure.) 



Leda minuta, Fabricius. 



Fossil — Leda clay, Montreal ; Rivi^re-du-Loup ; Greenland 

 (Moller) ; Labrador (Packard). 



Recent — Arctic seas, Gulf St. Lawrence ; coast of Nova Scotia. 



The fossil specimens occur abundantly with the last species at 

 E-ividre-du-Loup, and are quite similar to those dredged at Mur- 

 ray Bay. This was called L. caudata in my former lists. 



Lyda 2)yg'incea, Munster. 



Fossil — Leda clay. Green's Creek, Ottawa ; Saco ; Maine ; 

 also English Crag and other Glacial beds. 



Recent — North European seas ; but not yet recognized on the 

 American coast. According to Mr. Jefi"reys and Dr. Carpenter, 

 our drift shells are referable to the variety or species Yoldia ahys- 

 sicola of Torell. 



Leda (^Portlandia) glacialis, Gray; truncata, Brown. 



Fossil — Leda clay and Boulder clay, Montreal ; Quebec ; Ot- 

 tawa River ; Riviere-du-Loup ; St. John, N.B. ; Portland and 

 Saco, Maine ; also in Post-pliocene of Norway (Sars), and of 

 Scotland (Crosskey). 



Recent — x\rctic seas. 



This shell is most abundant, and generally diffused in the Leda 

 clay ; and the variety ordinarily found at Montreal and Riviere- 

 du-Loup is precisely identical with the ordinary Arctic form. A 

 long variety, called L. i7itermedia by Sars, is also found at Mont- 

 real, though rarely. A short variety, common in the Post plio- 

 cene at Murray Bay, is similar to the L. siliqua of Reeve from 

 the Arctic seas ; and young and depauperated varieties resemble 

 L. sulcifera of the same author. The abundant material from 

 the Post-pliocene shows that these are all varietal forms. 



This shell is Yoldia Arctica of Sars, but not of Moller and 

 Morch. It is 1^. ^nmca^a of Brown. It \^ Portlandia glacialis 

 of Gray, and Leda Portlandica of Hitchcock, 



