88 PLIOCENE MOLLUSCA. 



of N. incrasmta, but the fact that it was found at Oakley, where that species -is 

 unknown, is not in favour of such a view, nor does the opinion of the experts to 

 whom it has been shown support it. As it does not appear to be specially related 

 to any other Oakley form, except possibly as a dwarf variety of N. JJollfusii, I 

 figure it provisionally under the above name. 



Nassa incrassata (Strom). 



1768. Buccinum incrassaUim, Strom, Koug. Norsk. Vid. Selsk. Skr., vol. iv, p. 369, pi. xvi, fig. 25. 

 1848-72. Nassa incrassata, S. V. Wood, Mou. Crag. Moll., pt. i, p. 29, tab. iii, fig. 4, 1848 ; 1st SuppL, 



p. 12, 1872. 

 1853. Nassa incrassata, Forbes aud Hauley, Brit. Moll., vol. iii, p. 391, pi. cviii, figs. 3, 4. 

 1867. Nassa incrassata, Jeffreys, Brit. Conch., vol. iv, p. 351, pi. Ix.xxviii, fig. 1. 



Var. 13. Plate V, figs. 25, 26. 



1905. Nassa incrassata, Kobelt, Icon, schalentrag. europ. Meeresconch., vol. iii, p. 156, pi. xxvi, figs. 

 21—22. 



Varietal Characters. — Differs from the typical British form in its smaller size, 

 thinner texture, and more delicate sculpture ; the outer lip is thickened outside, 

 but not so strongly. 



Dimensions. — L. 9 mm. B. 5 mm. 



DistriMition. — Recent : reported from the Scilly Isles and the Algerian coast 

 (Tomlin) ; Christiania fiord. 



Fossil : Coralline Crag. Newbournian : Sutton, Felixstow. 

 Butleyan : Butley. Pleistocene : Norway. 



Remarks. — In the Wood collection at the Norwich Museum there are specimens 

 of a small and delicate variety of N. incrassata from the Newbournian Crag of 

 Sutton and Felixstow, and similar fossils are not infrequently met with in the 

 Butleyan deposits. They correspond with some shells from the Christiania fiord 

 which I have received from Dr. 0yen. In form and texture they approach N. 

 pygmsea,, but are not granulate, nor do they ever show the varix so characteristic 

 of that species. 



Mr. J. R. de B. Tomlin informs me that he has this unnamed variety of N. 

 incrassata in his collection from the Scilly Islands and that it has been dredged 

 in deep water off the Algerian coast. It seems to be common in the Christiania 

 region both as a Recent shell and in the Pleistocene beds, especially in the later 

 horizons. N. incrassata was reported by "Wood from the Coralline Crag, but I have 

 not seen it at Oakley, nor have Prof. Kendall or the brothers Bell found it at 

 Walton. 



The smaller Nassas of the Waltonian Crag are predominantly granulate, N. 



