152 ARCID^S. 



mistaken in giving Tenby as a locality. He collected 

 many shells there, but procured his specimens of N. 

 tenuis from the late Mr. G. B. Sowerby. It occurs in 

 all our upper tertiaries, and especially in deposits con- 

 taining shells of arctic species. The variety comes from 

 the deepest part of Loch Fyne and the Shetland sea. It 

 resembles N. nitida in shape, but is more convex. The 

 foreign distribution of this species and its variety extends 

 from Spitsbergen and Greenland to New England in the 

 Western hemisphere, and from Iceland along the whole 

 of the Scandinavian coast on our side of the Atlantic. 

 Danielssen has taken the variety at Vadso at from 30 to 

 160 fathoms. The typical form has been dredged by 

 Sars and M f Andrew in Finmark and Upper Norway, 

 by (Jrsted and Asbjornsen in Christianiafiord, and by 

 Malm on the coast of Bohuslan in Sweden, at various 

 depths from 55 to 100 fathoms. Philippi has recorded 

 it as a Calabrian fossil under the name of N. decipiens, 

 being probably one of the numerous relics of the glacial 

 epoch. 



Tor ell regards the N. expansa of Reeve (Belcher's 

 Arctic Voyage, vol. ii. p. 397, pi. 33. f. 2 a, b) as iden- 

 tical with the N. inflata of Morch, and perhaps also 

 with Hancock's species ; and he suggests the possibility 

 of its being a high-northern or arctic variety of the pre- 

 sent species. Having examined a great number of spe- 

 cimens of all acres collected by Dr. Torell in the arctic 

 seas and Iceland, which he refers to Reeve's and Morch's 

 species, and having compared the types of Hancock's 

 species, I have been unable to detect anything beyond 

 a slight varietal difference between these shells and 

 British specimens of N. tenuis. The arctic specimens 

 are exactly of the same shape as the Shetland variety 

 above described, but considerably larger. 



