﻿PLATE LXIV. 



Concavum-zone. 



FigS. 1 3. SONNINIA MARGINATA, S. BuckmftM. 



Fig. 1. — Side view of a well-preserved and very large example, showing the 

 increase in the size of the ribs on the last part of the whorl. (The ribs are some- 

 what too much reclined in the inner whorls.) Bradford Abbas, Dorset. My 

 Collection. (The figure is a copy of a photograph, and is rather less than 

 two-thirds of the original, namely, 201 mm. [7ff inches] against 312 mm. 

 [12-^- inches], the diameter of the fossil.) (Page 321.) 



Fig. 2. — Outline of the aperture, two-thirds natural size. 



Fig. 3. — Part of the last suture-line, natural size. 



