POSTGLACIAL, &>c, DEPOSITS OF CONTINENT. 467 



Norway, which are wholly wanting in the true glacial beds, 

 appear abundantly in the postglacial deposits. It is remarkable, 

 however, that some molluscs which in postglacial times lived 

 in great numbers on the south coasts of Norway have now 

 retired to the west coast (Kellia rubra [Cardium], Mont., Tapes 

 virginea [Venus], Mont.) ; some to the same and the north coast 

 {Lima excavata [Ostrea], Fal., Pecten islandicus, Miill., P. vitreus, 

 Chemn., Pholas crispata, Linn., Margarita undulata, Sow.) A 

 few species {Caecum glabrum [Dentalium], Mont.) 1 which occur 

 very abundantly in the shell-banks at Kirkoen in Norway have 

 hitherto only been found living on the west coast (Bergen), and 

 are there somewhat scarce. Malm, however, notes Catcum glab- 

 rum as still living at Bohuslan (Sweden). The elder Sars, to 

 whose papers 2 I am chiefly indebted for these notes, draws 



In Glacial shell-banks. In Postglacial shell-banks. 



Buccinum granlandicum (Chemn.) . Represented by B. undatum (Linn.) 

 Trophon clathratus (Linn.), var. major Do. T. clathratus, var. minor. 



The Glacial are similarly contrasted with the Postglacial clays, thus :— 



In Glacial marly clay. In Postglacial shelly clay. 



Yoldia arctica (Gray) Wanting. 



Siphonodentalium vitreum (Sars) .... Do. 



Dentalium abyssorum (Sars) ..... Scarce. 



Area raridentata (Wood), var. major . . . Extremely scarce. 



Leda pernula (Miill. )...... Do. 



Yoldia pygmaxt, (Miinst.), var. gibbosa (Smith) . Do. 



Natica grcenlandica ...... Do. 



Nucida tenuis Wanting. 



The foregoing species are all highly characteristic of the Glacial beds. Again, 

 the most characteristic deep-water forms of the Glacial and Postglacial clays are 

 as follow : — 



Glacial marly clay-beds. Postglacial shelly clays. 



Yoldia pygmcea, var. intermedia. Isocardia cor (Linn.) 



Ledapernida. Cardium elcgantulum (Beck). 



Nucida tenuis. Nccera cuspidata (Olivi). 



Area raridentata, var. major. Rhynconella psittacea (Gmelin). 



Siphonodentalium vitreum. Waldheimia septigera (Loven). 



Dentalium abyssorum. 



Ophiura Sarsii (Luth. ) 



1 Sars mentions also Odostomia plicata, but according to Jeffreys this is a 

 wrong determination, and should be 0. albella, which ranges from Norway to 

 the Mediterranean. — British Conchology, vol. iv. p. 122. 



2 See especially " Iagttagelser over den postpliocene eller glaciale Formation,' 



