IN THE LOWER CARBONIFEROUS OF SCOTLAND. 



39 



Plate V. 



Fig. 6. Diphyphyllum latiseptaium, M'Coy, transverse section. 



7. , var. giganteum, transverse section. 



8. , , longitudinal section of corallites. 



9. , var. mterruptum, transverse section. 



10. gracile, M'Coy, transverse section. 



Discussion. 



Prof. Duncan, after drawing attention to Mr. Thomson's industry, 

 stated that the communication settled the long-disputed value of 

 Diphyphyllum, Lonsd. Lonsdale diagnosed the genus from in- 

 different specimens, and yet clearly established the absence of a 

 columella and the presence of fissiparity in the forms. Mr. Thom- 

 son's beautiful specimens prove that Lonsdale was correct, and 

 in addition show that there was also gemmation. It is now evident 

 that the opinions of Milne-Edwards and Jules Haime about the 

 genus are incorrect. In drawing attention to the different aspects 

 of the calices of the Rugosa and of sections made lower down in 

 the corallites, Prof. Duncan remarked that Mr. Thomson placed too 

 great a classificatory value on the endothecal structures, which vary 

 in the same coral. 



Dr. Hinde inquired whether the diagrams exhibited related to 

 distinct species or represented characters drawn from different 

 species. Is it the case that both fissiparity and calicular gemmation 

 occur in the same species ? 



Prof. Duncan thought the diagrams were intended to be general. 



Prof. Rupert Jones expressed himself favourably with regard to 

 the paper and the specimens. 



The President expressed his regret that Mr. Thomson was not 

 present to receive the personal congratulations of the masters of 

 palseontological science upon his interesting communication. 



