Platr VI. 



Kit.'. 1 _'. Xin'inij<>)n>r(i sp.. showing si/..' ami outer form of the corallites in 



Iran-ver-M- anil longitudinal section I.". 



Fig. !. I-'uroxift's d'. helderbergiae HAM., longitudinal section, showing tin- 



closely arranged talmlue, X2 II 



Fig. -1. Tltecin s>rnnli'fi'n<unt (n>im., part of the surfnoe, >( 2 l.'i 



Kij:. " 7. ('iii-liiiliinii nrcticnni DOT. sp. from Series A, east coast of North Devon 5 



I IL;. .">. A 1'raijiiient of a stronyly worn ventral valve showing the 



length of the median septum. 

 Fig. I). A Iriigment of a dorsal valve with a line showing the convexity 



in transverse section. 



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

 tudinal sei-lion. 



Fig. 8. Cyrtina a.ini nov. sp., from upper Devonian heds of Beechey Is- 



land. L-inca-t<T Sound . . 47 



