Plate VI. 



Page 

 Fig. 12. Syringopora sp., showing size and outer form of the corallites in 



transverse and longitudinal section 15 



Fig. 3. Favosites cf. helderbergiae HALL, longitudinal section, showing the 



closely arranged tabulae, X 2 11 



Fig. 4. Thecia swinderenana GOI.DF., part of the surface, X 2 15 



Fig. 5 7. Conchidium arcticum nov. sp. from Series A, east coast of North Devon 5 

 Fig. 5. A fragment of a strongly worn ventral valve showing the 



length of the median septum. 

 Fig. 6. A fragment of a dorsal valve with a line showing the convexity 



in transverse section. 



Fig. 7. Line showing the convexity of another dorsal valve in longi- 

 tudinal section. 



Fig. 8. Cyrtina gjoai nov. sp., from upper Devonian beds of Beechey Is- 

 land, Lancaster Sound , 47 



