﻿PLATE XXI. 



1. Rhynchonella acuminata, var 



2. — — 



3. — — 

 4 — 13. — — 



14 — 20. — — 



mesogonia, Phillips. From the Carboniferous 

 limestone of Clitheroe. 



From the same locality. Gilbert- 

 sonian collection. British Museum. 



var. with two ribs on the fold ; 

 same collection and locality. 



var. plicaia. A number of vari- 

 ations in shape more or less 

 plicated, from Clitheroe. Gilbert- 

 sonian collection. British 

 Museum. 



var. platiloba, Sowerby. From Cli- 

 theroe and Kildare. 



