TEREBRA. COLUMBELLA. 91 



The columella is umbilicated, and has a canal 

 beneath it. 



" The Terehra genus is turreted ; very acute 

 at the apex. (Plate 9.) 



"■ The family Collumellaria is next in order. 

 The cajicd now disappears at the base of the shell, 

 but there is a slope and folds on the columella. 

 We have reached the large genus Voluta of 

 Linnaeus, greatly reduced by withdrawing the 

 following genera : 



Coiumbella, ^ 



Mitra, 



Cymha^ 



Melo, J Voluta. 



Voluta^ 



Marginella, 



Volvaria, 



" The shells of Coliimhella are of small size ; 

 two species are very common in collections. C. 

 mercatoria is a little shell striated transversely ; 

 the outer lip is thickened in the middle, and 

 toothed ; the columella is plaited : the animal is 

 furnished with an operculum. 



" Columhella nitida is another pretty species, 

 smooth and shining: you may perceive the 

 generic marks if you look closely — two small 

 folds on the pillar-lip, and the swelling, toothed, 



