176 MOLLUSCA FROM THE CRAG. 



authors, this shell is spoken of as perfectly smooth ; but their examination must 

 have been of ill-preserved individuals ; the striaB being very minute and little 

 impressed, they are easily obliterated. 



A specimen from the Mammaliferous Crag, near Norwich (fig. 1 b), was found 

 by Mr. Wigham ; it has a diameter greater than three fifths of its axis, with a 

 curved or semicircular outer lip, and is, I imagine, only a variety of this species. 



5. Bulla concinna. S. Wood. Tab. XXI, fig. 6, a — c. 



Bulla concinna. S. Wood. Illust. in Mag. Nat. Hist. 1839, p. 463, pi. 7, fig. 7. 

 — S. Wood. Catalogue 1842. 



B. Testa minutd, subcylindraced, tenui, frayili; transversim tenuissime, striata, et 

 lonyitudinaliter decussatd ; vertice umbilicato ; spird inclusd ; columella obsolete uniplicatd. 



Shell small, subcylindricaL thin, and fragile, finely striated transversely, and 

 decussated by the lines of growth ; vertex umbilicated ; spire hidden ; inner lip 

 slightly replicate, with an obsolete fold upon the columella. 



Axis, -g- of an inch ; diameter, f of its length. 



Locality. Cor. Crag, Sutton. 



Unfortunately, since the publication of the description of this species at the 

 above references, I have not found a specimen larger or more perfect than what I 

 then possessed. It is very probable that this may be the young of Bulla clathrata, 

 Defrance, B. Tarbelliana, Grateloup, Bord. foss. p. 58, f. 29-30. The principal 

 difference appears to be in the size, although, from the figures, our shell is rather 

 less cylindrical, with an obtuse fold upon the columella, which is most visible in 

 broken specimens. I have left it with my own name for the present, until some 

 better specimens are found to confirm either the one or the other. 



6. Bulla truncata. Adams. Tab. XXI, fig. 3, a — c. 



Bulla truncata. Adams. Linn. Trans. V, t. 1, fig. 1-2, 1/97. 



— — Mont. Test. Brit. p. 223, t. 7, fig. 5, 1803. 



— retusa. Maton and Rack. Linn. Trans, vol. viii, 1807. 

 Volvaria retusa. Brown, Illust. Brit. Conch, pi. 38, fig. 17-18, 1827. 

 Bulla truncata. Flem. Brit. Animals, p. 293, 1828. 



— semisulcata. Phil. En. Moll. Sic. vol. i, p. 123, t. 7, fig. 9, 1836. 



— subtruncata. S. Wood. Illust. Mag. Nat. Hist. pi. 7, fig. 9, 1839. 



— truncata. Phil. En. Moll. Sic. vol. ii, p. 96, 1844. 



— — S. Wood. Catalogue 1842. 

 Cylichna truncata. Lovcn. Ind. Moll. Scand. p. 10, 1846. 



B. Testa pusilld, cylindricd, Iceviyatd ; basi vise dilatatd ; aperturd superne anyuste 

 Jineari ; in/erne paululum latiore ; vertice truncato, vel late umbilicato ; spird distinctd, 

 plica ad basim columella parum manifestd. 



Shell minute, cylindrical, and smooth, with a little contraction in the middle, or 



