﻿BRITISH FOSSIL CEPHALOPODA. 



Plate XII. 



Fig. 



1. Orthoceras ardvellense. — From the Bala Series, Ardwell. In the Museum 



of Practical Geology. 



2. Orthoceras excentricum. — From the Wenlock Shale (?), Clytha, Usk. In the 



Museum of the Cardiff Naturalists' Society, a, end view of septal surface. 



3. Ibid. — End view of Sower by 's type. From the Wenlock Shale, Radnor. In 



the Museum of the Geological Society. 



4. Orthoceras bullatum. — From the Upper Ludlow, Ludlow. In the Ludlow 



Museum. Example showing striae. 



5. Ibid. — From the Aymestry Limestone, Ledbury. In the collection of Dr. 



Grindrod. Section showing the septa. This example is ornamented with 

 riblets. 



6. Orthoceras subgregarium. — From the Bala quartzites, Cong. A copy of 



M'Coy's figure. 



7. Orthoceras ascendens. — From the Bala Limestone, Chair of Kildare. In the 



Museum of Practical Geology. 



8. Orthoceras audax. — From the Bala Beds, Rhiwlas. In the Museum of 



Practical Geology. 



9. Orthoceras subconicum. — From the Upper Llandovery, Tortworth. In the 



Museum of the Geological Society. Sowerby's type of 0. conicum 



