1 20 GENUS XXVI. MUREX. 



Fasciolaria. Shell somewhat spindle-shaped, with a channel 

 at the base, and without sutures, having on the pillar two 

 or three very oblique folds (see Murex Tulipa, f. 90). 



Plevrotoma. Shell somewhat spindle-shaped, the aperture 

 terminating at the base in a long canal, with a notch or 

 hollow at the upper part of the right lip (see Murex 

 habylonius, f. 91). 



Cerithium, Shell tapering; the aperture oblique, terminating 

 at the base in a short canal, truncated or recurved, with a 

 groove at the upper end of the right lip (see Murex Aluco, 

 /.92). 



Perhaps here we may mention Lamarck's genus Clavatnla, 



described as follows : 



Clavatula. Shell somewhat turrited, rough, having the aper- 

 ture terminated at the lower end by a short canal or hollow, 

 with a notch on the right lip near the summit (see Chenm. 

 vol. 11. t. 190. f. 1831 and 1832). 



