232 Dr. Gwyn Jeffreys on Arctic 



mark, 40-150 fms. (Lov^n, Sars) : White Sea and coasts of 

 Russian Lapland (Middendorff) : Gulf of St. Lawrence, 150 

 fms. (Whiteaves) : ' Porcupine ' Expedition, 1869, 420-542 

 fms., young ; 1870, Bay of Biscay, 257-539 fms., young : 

 Arctic Expedition, 5i-35 fms. (Feilden and Hart). 



Fossil. Tangy Glen, W. Scotland (Robertson and Cross- 

 key) : E. Scotland, 30-40 ft. deep : Elie, a few ft. below the 

 surface (Jamieson). 



The shell is certainly not " equivalve," as Sowerby de- 

 scribed it. It is the P. vitreus of Gray in the ^ Supplement to 

 the Appendix of Parry's First Voyage,' but not Chemnitz's 

 species of that name. 



Leda jpernula^ MuUer. 

 Arcapernula, Miill. in Beschaftigungen naturf. Freunde, vol. iv. p. 35. 



Yar.falcula. Shell sickle-shaped, longer (from the beak 

 to the front margin) and flatter than the variety Jachsonii of 

 Gould or huccata of Steenstrup ; the " rostrum " or point is 

 short, blunt, and more or less upturned in the adult ; front 

 margin curved. 



St. No. 1 (Moss). 



Recent. Spitzbergen (Torell, Eaton) : Wellington Channel 

 (Belcher). The typical form and other varieties inhabit both 

 sides of the North Atlantic as well as the North Pacific, at 

 depths of from 20 to 150 fms. : ' Porcupine ' Exp. 1869, 

 251 fms.; 1870, Bay of Biscay, 305-517 fms.: ^Valorous' 

 Exp. 15-175 fms. : Arctic Exp., 5^ fms. (Feilden). 



Fossil. Post-tertiary or "glacial" beds in the North of 

 England, N. Wales, Ireland, Scotland, Scandinavia, and 

 Canada, surface to 320 ft. : Moel Tryfaen, 1330-1360 ft. 

 (Darbishire). 



Variable in shape and sculpture. Having many synonyms, 

 or polyonomatous. 



Leda frigidaj Torell. 



Yoldia friqida, Tor. Bidr. t. Spitzbergens Molluskfauna, p. 148, t. 1. 

 f. 3 (1859). 



St. No. 3 (Feilden). 



Recent. Spitzbergen, 30-60 fms., and Greenland, 250 

 fms. (Torell) : Iceland (Mus. Copenhagen) : Finmark, 200- 

 300 fms. (Sars) : Shetland, 60 fms. (J. G. J.) : Gulf of St. 

 Lawrence, 150 fms. (Whiteaves) : ' Porcupine' Exp., 1869, 

 114- 1360. fms. ; 1870, Bay of Biscay, 227-1095 fms. : ' Valo- 

 rous ' Exp., 175 fms. 



Yoldia nana of M. Sars. 



