DESCRIPTION. 
173 
towards the upper part; lower part of the outer 
lip furnished with 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 false rather than of a 
perfect tooth. 
Fig. 3. B. stromhiforme. 
Shell oblong, longitudinally plaited ; outer lip 
separated above, expanded, thickened ; aperture 
toothed. 
Nondescript, 
Specimen dark brown with a reddish tinge, 
aperture white ; upper part of the columella and 
margin of the outer lip brown. 
Shell smooth, plaits broad, folded towards the 
aperture ; upper margin of the whorls surrounded 
with a tumid belt ; lower part of the body trans- 
versely sulcated ; columella 4-toothed, outer lip 
with nine teeth ; apex pale, diaphanous. 
Habitat unknown. 
