GENUS XXX. NERITA. 133 



no umbilicus ; the aperture entire and half round ; the 

 pillar nearly transverse, with an acute and generally den- 

 tated edge (see Nerita poliia, pi. 9. f. 11 9). 

 Natica. Shell nearly globular, umbilicated, the left lip thick 

 towards the umbilicus; the aperture entire and half round; 

 the pillar oblique, without teeth (see Nerita Canrena, 

 pi. 9. /. 11 8> 



