134 POPULAR CONCHOLOGY. 



them, it will be advisable to give representa- 

 tions of a few different kinds of univalve shells, 

 with a description of the parts constituting 

 them, and the names by which they are known, 

 as in giving an account of the variations which 

 exist in the different genera many of these will 

 be referred to. In fig. 1. is delineated the sim- 

 plest form, that of a Patella, in which the parts 

 necessary for reference are but few. A is the 

 apex, B the mouth or aperture, of which CC is 

 the margin. The exterior and interior are suffi- 

 ciently obvious. In figures 2. to 7., which are 

 turbinated or spiral shells, and of a more com- 

 plicated form, a greater number of terms have 

 been adopted to mark the variations which oc- 

 cur. A is the apex, B the mouth or aperture, 

 which in fig. 2. is entire ; in fig. 3. notched ; in 

 fig. 4. channelled. T> is the spire, formed of a 

 greater or less number of whorls, the intersec- 

 tions of which, or where they wrap over, are 

 called sutures E. r is the right or outer lip ; G, 

 the left, inner, or columella lip ; H, in fig. 3., is 

 the notch ; I, in fig. 4., is the channel or canal ; 

 K, in figs. 5. and 6., the umbilicus; L, in fig. 7., 

 is the columella, or pillar, which can only be 



