GASTEROPODA. 7 



removal. Mr. Bell also says that fig. 10 a, c, of the same plate may be referred to 

 Fusus Olavii, Beck, and considered a distinct species. 



The principal character, indeed I believe the only one, by which tortuosus can be dis- 

 tinguished from either gracilis or propinquus is the greater convexity of the volutions ; 

 the form of the canal being similar in each with the volutions covered by regularly broad- 

 spiral striae. I have here had represented as above (fig. 2 a) the specimen from 

 Dr. Reed, and which, in outward form, varies from the figure in the Crag Moll, as 

 also from that given as mentioned by Lovell Reeve. I think it may be considered only as 

 a variety ; it is said to have come from Waldringfield. Fig. 2 b of my present plate is the 

 representation of a specimen of my own found by myself in the Red Crag at Sutton many 

 years ago, and this I now think is only a slight distorted form of tortuosus, as I have two 

 others similar in the volutions, but not so perfect, and thought it only a variety, not of 

 sufficient importance to deserve a figure ; but so many separations having been made out 

 of a group of shells which probably may be united under the name of Sipho, I have had it 

 here figured and have endeavoured to group these shells together under that name, 

 which have been found in the Upper Tertiaries of the east of England, viz. : 



Trophon (Sipho) Islandicus? C/tem. 2nd Sup., tab. ii, fig. 3. Red Crag. 



Olavii, Seek. Crag Moll., vol. i, p. 46, tab. vi, fig. 10 a, c. Red Crag. 



gracilis, Da Costa. 2nd Sup., tab. ii, fig. 4. Cor. Crag, 

 propinquus, Alder. App. Crag Moll., tab. xxxi, fig. 3 a. b. Cor. Crag. 



id. Sup., tab. vii, fig. 21, sinistral. Red Crag, 

 id. 2nd Sup., tab. ii, fig. 5. Cor. Crag. 

 Sarsii, Jefl. Sup., p. 23, tab. i, fig. 9. Red Crag. 



tortuosus, L. Reeve. Crag Moll., vol. i, tab. vi, fig. 10 b. Red Crag. 



id. Sup., tab. ii, fig. 15 a. Red Crag. 



id. 2nd Sup., tab. ii, fig. 2 a, b. Red Crag. 



Sabini, Hancock. Sup., tab. ii, fig. 1 5 c. Bridlington. 



ventricosus, Gray. Sup., p. 22, tab. iii, fig 4. Bridlington 



Leckenbyi, S. Wood. Sup., p. 24, tab. vii, fig. 1. Bridlington. 



The whole of these may very probably be only inconstant varieties of Islandicus, but 

 I have figured them under the names of their authors to show their occurrence in the 

 deposits embraced by my Monograph. T. Leckenbyi of myself stands in this respect on 

 an equal footing with the other so-called species given above. 



Note. Sipho, Klein, 1753. This name is previous to our starting point, the 12th 

 edit, of Linne, but it appears now to be adopted by many of our conchologists. 



