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BULLA. 



A. Birostrate, or produced both ways. (Plate 



XIV. Fig. 5.) 



B. Caudate. (Fig. 6.) 



C. Without any elongation. (Fig. 7.) 



D. Tapering. (Fig. 8.) 



Shell univalve, convolute, unarmed. Aperture 

 subcoarctate, oblong, longitudinal, entire at the 

 base. Columella oblique, smooth. 



The diagnosis of this genus is, perhaps, least 

 accurately determined of any. Some species ap- 

 proach so nearly to Cyprsea, others to Helix, to 

 Buccinum, or to Murex, that it is very difficult to 

 trace out the line of demarcation. The most com- 

 mon character of Bulla is an inflated, egg-shaped 

 body ; and it will be found to differ from those 

 genera which it most resembles, in some one, if 

 not in more essential points. 



To render this genus in some degree more sys- 

 tematical, it is proposed to apportion it into the 

 four divisions, of which the forms are given in the 

 plate of Bulla. Though some, even many of the 



