﻿PLATE LXVIII. 



Concavum-zone. 

 Figs. 1, 2. — Sonninia mode st a, 8. Buckman. 



Fig. 1. — Side view of an example in which the last quarter- whorl is abnormally 

 costate, presumably the result of injury. Without these costse 1 the shell exactly 

 represents the ordinary form of the species. Bradford Abbas, Dorset. My 

 Collection. (Owing to breakage neither side of the specimen affords complete 

 details, and therefore it has been necessary to combine the features of both sides 

 of the fossil in order to show its characters properly.) (Page 325.) 



Fig. 2. — Outline to show the shape of the whorls in front view, taken from the 

 place marked O- 



1 The arcuate shape of these costse is incorrect ; they should be nearly upright. The last rib is 

 too conspicuous ; it should be somewhat tuberculate at its middle. The penultimate rib should have 

 been rather less conspicuous than the last ; the antepenultimate and its predecessor are much too 

 conspicuous ; the forerunner of these is hardly conspicuous enough. 



