﻿PLATE XX. 



Pie. 

 1. Trif/onia tenuitexta,hyc. Portland Limestone, Isle of Portland. (Page 90.) My 



cabinet. 



1 a. „ „ A very young example enlarged one diameter. Portland Lime- 



stone, Devizes. Coll. Cunnington. 



3. ,, Joansi, Lye. Mould with surface ornaments. Lower Calcareous Grit, 



Brora, N.B. (Page 82.) My cabinet. 



3. „ „ Specimen in two portions from the same formation and locality. 



Coll. British Museum. 



4. „ „ An entire specimen from the same formation and locality. Coll. 



Rev. J. M. Joass. 



5. „ excentrica. Park. Young example. Blackdown. (Page 94.) Coll. 



British Museum. 



6. „ „ A very young example. Greensand, near Collumpton. Coll. 



Vicary. 



7. „ Mic/ielottiiDe hov. (Variety.) Mould of external cast. Portland Oolite, 



Devizes. (Page 92.) Coll. Cunnington. 



