﻿BRITISH FOSSIL CEPHALOPODA. 



Plate XX. 



Fig. 



1. Cyrtoceras approximatum. — From Wenlock Beds (?), Dudley. In the British 



Museum, a, the septal surface ; siphuncle undiscoverable. 



2. Trochoceras ? ciNEREUM. — From the Bala Beds, Desertcreat. In the Museum 



of Practical Geology. 



3. Cyrtoceras macrum. — From the Bala Beds, Rhiwlas. In the Museum of 



Practical Geology. 



4. Cyrtoceras alternatum. — From the Bala Beds, Bala. In the Museum of 



Practical Geology. 



5. Cyrtoceras iislequiseptum. — From the Bala Shales, Desertcreat. In the 



Museum of Practical Geology. The type of Portlock's Phragmoceras 

 Brateri. a, the outline of the section. 



6. Cyrtoceras intermedium. — From the Lower Ludlow, Ludlow. In the Museum 



of the Geological Society. One of the specimens figured by Sowerby as 

 Phragmoceras arcuatum. a, outline of present section. 



7. Cyrtoceras subarcuatum. — From the Bala Shales, Desertcreat. In the Museum 



of Practical Geology, a, outline of the section. 



8. Cyrtoceras injsquiseptum. — From the Bala Shales, Desertcreat. In the 



Museum of Practical Geology. Portlock's type. 



