Plate VI. 



Page 

 Fig 1—2. Sjjringopora sp., showing size and outer form of the coralhtes in 



transverse and longitudinal section .... . . . . 15 



rig. 3. Favo.^ites cf. helderbergiae Hall, longitudinal section, showing the 



closely arranged tabulae, X 2 . ■ • ■ . . 11 



Fig. 4. Thacia swinderennna Goi.df., part of the surface, X 3. . . , 1.5 



Fig 5 — 7. (Jonchidiiini (ircticuni 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. (). A iragnient of a dorsal valve with a line showing the convexity 



in transverse section. 

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

 tudinal section. 

 Fig. 8. Cifiiina mdni nov. sp., from upper Devonian heds of Beechey Is- 

 land, Lancaster Sound . ... 47 



