280 POPULAR BRITISH CONCHOLOGY. 



where the whorls meet and sometimes form a pillar, is 

 named the columella ^ or columellar lip. The aperture is 

 the opening or entrance to the hollow part of the cone, into 

 which the animal retreats. Its edge, as a whole, is called 

 the joeritreme. The outer side, or that which is furthest 

 from the axis, is called the outer lij} : the inner, or the one 

 which either forms or is contiguous to the axis, is called 

 the inner, or columellar lip. 



THE SPIRE, 



Composed of the volutions above the aperture, is described, 

 as a whole, as being long or short, in proportion to the 

 aperture ; as consisting of few or numerous volutions ; as ta- 

 perin(jj conical, or ventricose. Its apex, or nucleus, is obtuse 

 or blunt, acute or sharp. In some species of land-shells it 

 falls off after the shell is fully formed ; it is then said to be 

 deciduous. In Planorhis and some other shells, instead of 

 being produced into a pyramid or dome, it is depressed and 

 even concave : when shaped like a teat or nipple it is papil- 

 lary, and when more rounded it is mamillated. 



THE WHORLS 



Of the spire are described as more or less rapidly enlarged ; 



