BULLA. DIPPER. 23 



crown, without external volutions : aperture very narrow, 

 reaching the whole length of the shell, dilated into an oval 

 at the base : resembles the last, but is not so cylindrical, 

 and the length, which is about a quarter of an inch,* is 

 double its breadth. 



Western coasts, Scotland, and Dublin hay. v. v, 



9. Bulla retusa, Truncate Dipper. 



Bulia truncata. Montagu, pi. 7- f. 5 Linn. Trans, v. 

 pi. 1. f. 1, 2 JFflflter, f. 62. 



Shell somewhat cylindrical, white, rather opake, finely 

 and regularly striate longitudinally on the upper halt' only, 

 the lower part keing nearly smooth : crown abrupt, with a 

 large perforation in which the volutions are visible : aper- 

 ture reaching the whole length of the shell, very narrow, 

 something contracted about the middle and dilated into an 

 oval at the base, where the outer-lip is a little spread over 

 the pillar: length hardly two lines ; breadth more than half 

 as much. 



Western coasts, Dublin bay, and North Britain, v. v. 



10. Bulla obtusa. Obtuse Dipper. 



Montagu, pi. 7- f- 3 Dorset Cat. pi. 18. f. 14IFalker, 

 f. 61. 



Shell somewhat cylindrical, opake, white or covered with 

 a chesnut-brown skin, longitudinally wrinkled ; crown ob- 

 tuse, with four or five very slightly produced volutions : 

 aperture extending nearly but not quite to the whole length 

 ot the shell, narrow, a little compressed in the middle, and 

 dilated into an oval at the base ; inner-lip thickened, smooth, 

 white : length about two-tenths of an inch j breadth half its 

 length. 



Walker's figure is an excellent representation of this 

 shell : but Mr. Jacobs, who furnished the author with the 

 descriptions, mistaking it for aVoluta, it has hitherto been 

 quoted for the V. alba, to v which it has no resemblance. 



Western coasts, Dublin bay, and Scotland, v. m. 



1 11. Bulla aperta. Wide Dipper. 



Da Costa, pi. 2.f.'3 Montagu, Vignette 2. f. 1 Dowo- 

 van, pi. 120. f. [Dorset Cat.^pl 22! f. o. 



Shell somewhat orbicular, extremely thin and brittle, 



transparent, 



