GASTEROPODA. 175 



might be said to form a passage into Ovula, through Ov. patula, which has a non- 

 reflected outer lip. The shell differs from the general character of this genus only 

 in the acuminated form of the upper part of the outer lip, with the fold at the base, 

 as in Bulla, and not above, as in Ovula, and it is not regularly bicanaliculated. The 

 striae are most distinct upon the base of the volution, but there are also a few 

 visible at the upper part, whilst, upon the body of the shell, at least in my 

 specimens, it is smooth and glossy.* 



4. Bulla cylindracea. Penn. Tab. XXI, fig. 1, a — c. 



Bulla cylindkacea. Pennant. Brit. Zool. vol. iv, t. 70, fig. 85, 1776. 



— Mont. Test. Brit. p. 221, t. 7, fig. 2, 1802. 



— Don. Brit. Shells, vol. iv, t. 120, fig. 2, 1805. 

 Bulla convoluta. Broc. Coq. foss. Subapenn. t. i, fig. 7, 1814. 



— J. Sow. Min. Conch, t. 464, fig. 1, 1824. 



Volvaria cylindrica. Brown. Illust. Brit. Conch, pi. 38, fig. 36-37, 1827. 

 Bulla convoluta. Grat. Not. sur la Fam. des Bull. pi. 3, fig. 37, 1837. 



— Phil. En. Moll. Sic. vol. ii, p. 97, 1844. 



— Nyst. Coq. foss. de Belg. p. 454, pi. 39, fig. 6, 1844. 

 Bulla Cylindracea. S. Wood. Illust. in Mag. Nat. Hist. pi. 7, fig. 8, 1839. 

 Cylindrella alba. Swains. Treat, on Malac. p. 326, fig. 94 b, 1S40. 

 Cyliciina cylindracea. Loven. Ind. Moll. Scand. p. 10, 1846. 



B. Testa cylindrica cr asset ; tenuissime striata; ajpertura lineari, versus basim parum 

 dilatatd ; vertice truncato, depresso ; spird occulta ; columella obtuse unipllcatd. 



Shell elongato-cylindrical, convolute, upon a nearly horizontal axis, covered 

 with fine, transverse, regular striae ; aperture linear, dilated at the base, with an 

 obtuse fold upon the columella ; vertex depressed, concave, with a hidden spire. 



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



Locality. Cor. Crag, Sutton. 



Red Crag, Sutton. Recent, British Seas. 



This species is very abundant at one locality in the Coralline beds, but is very 

 rare as a Red Crag shell. The volution being nearly horizontal, the outer lip is carried 

 above the spire, and there is a little inflection of the shell at that part which covers 

 what would otherwise be a perforation ; a small hole may be occasionally seen, but 

 it is generally closed. 



Among my Crag fossils, as well as among my recent specimens, are individuals 

 both smooth and striated, but the condition of the latter is, I believe, dependent 

 upon the state of preservation of the exterior. In a recent state it is covered by an 

 epidermis, and then the striae are well seen. In the description by the above-quoted 



* Since the above was written I have seen the recent shell from the Mediterranean, which is rather 

 more cylindrical, less regularly fusiform, and the pointed portion of the upper lip less acuminated, with 

 a few faint striae upon the base ; such differences are probably only the result of locality, and cannot be 

 considered specific. 



