DESCRIPTION. 173 



towards the upper part ; lower part of the outer 

 lip furnished v\'ith the rudiments of a spine or tooth. 



Habitat unknown. 



The specific name Pseudodon has been assigned 

 to this shell because the thickened internal rib, 

 which is situated in the same part as the spine in 

 B. Monodon, does not project beyond the margin, 

 and has the appearance of "a, false rather than of a 

 perfect toolh. 



Fig. 3. B. stromh'iforme. 



Shell oblong, longitudinally plaited ; outer lip 

 separated above, expanded, thickened ; aperture 

 toothed. 



Nondescript. 



Specimen dark brown with a reddish tinge, aper- 

 ture white ; upper part of the columella and mar- 

 gin of the outer lip brown. 



Shell smooth, plaits broad, folded towards the 

 aperture J upper margin of the whorls surrounded 

 with a tumid belt ; lower part of the body trans- 

 versely suicated j columella 4-toothed, outer lip 

 with nine teeth ; apex pale, diaphanous. 



Habitat unknown, 



