GASTEROPODA. 45 



apical one, which is smooth; the costse are prominent, 10 — 12, and the striae are 

 carried over the ribs when the surface has not been rubbed and worn. 



Pleurotoma nebulosa, S. Wood. Crag Moll., vol. i, p. 60, Tab. VII, fig. 10, as 



Clavatula nebula. 



Localities. Red Crag, Sutton and Butley. 



Mr. Jeffreys, ' Brit. Conch.,' vol. iv, p. 386, observes that this Crag shell does not 

 agree with the living species nebula of Montague. In this I am disposed to agree with 

 him, and, not being able to identify it with any other known shell, I have assigned to it 

 the above name. 



Pleurotoma nebula, Mont. Supplement, Tab. VII, fig. 7. 



Locality. Coralline Crag, Sutton. 



The above figure represents a specimen in my cabinet from the Coralline Crag of 

 Sutton, of what, I believe, may be truly referred to the existing species of this name, 

 agreeing with the Mediterranean variety of it. 



Pig. 9, Tab. VI, of this Supplement represents the fragment of a shell which Mr. 

 Canham had obtained from the Red Crag of Waldringfield. I felt induced to have it 

 figured in order to call attention to its existence, and to leave nothing unnoticed up to 

 the present time that has been found in the Upper Tertiaries of the East of England. 

 This fragment has been named and published in the { Ann. and Mag. Nat. Hist.,' 1871, 

 by Mr. Bell, under the name of PI. violacea var. gigantea — PI. arctica, Adams. There 

 were two specimens, but both unfortunately in the same mutilated condition, with nothing 

 but the last volution remaining, and this is entirely destitute of sculpture, showing only 

 that it possessed a sinuation at the upper part of the outer lip. The reference of these 

 fragments to violacea by Mr. Bell does not quite meet with my approval, as the shell to 

 which they belonged must have exceeded an inch in length, while the longitudinal dimen- 

 sions of violacea, as given by the American authors, are only n>ths of an inch ; and there 

 is no ornament on our present shell to assist in its determination. There is a fragment of 

 a shell in my cabinet from the Cor. Crag (which much resembles our Red Crag shell), and 

 this has distant and obsolete costae, and covered with fine spiral stria?, which might have 

 been upon the Red Crag shell. As Mr. Bell has given to this the name of arctica, I 

 have not thought it necessary to alter it, still I think it might be called ambigua. I doubt 

 its specific connection with violacea. 



