﻿PLATE XXIII. 



1, 2. Rhynchonella pleurodon, Phillips. From the Carboniferous limestone of 



Bolland. 



3 — 5. — — From Bolland and Settle. 



6. — — A specimen with nine ribs on the mesial fold. 



Bolland. British Museum. 



7. — — From Kerry, Ireland. 



8 — 1 1 . — ■ — Young shells from' Settle, in Yorkshire. 



12. — - — A globose variety, in which the ribs do not attain the 



extremity of the beaks. 



13, 14. — var. T. ventilabrum, Phillips. After the figure in 



the ' Geology of Yorkshire.' 



15. — — = Terebralula Mantics, Sow. From the original 



specimen in the collection of Mr. J. de C. Sowerby. 

 It is a malformation of Rh. pleurodon. 



16. — — var. triplex, M'Coy. From the Carboniferous 



shale, near Carluke, Lanarkshire, Scotland. 



17. — - From Professor M'Coy's type of A. triplex. 



18. — ■ — A malformation, the sinus being twisted to one side. 



Carluke. 



19 — 21. — var. Davreuxiana, De Koninck. Carboniferous 



limestone, Gilling, Yorkshire, in the collection of Mr. 

 E. Wood. 



22. — ? From the* Carboniferous limestone of Tvviston, 



Lancashire, and collection of Mr. Parker. I am 

 uncertain as to the species to which this remarkable 

 specimen should be referred, a single example only 

 having been hitherto discovered. 



