30 Mr. R. Etheridge on Carboniferous Mollusca. 



supplemental deposit. His opportunities of study, whether of 

 Millepora or of Stromatopora, would seem, from his own state- 

 ments, to have been somewhat limited. This may possibly 

 account for the somewhat extraordinary identification of two 

 classes of organisms which scarcely resemble each other in 

 any thing except in being calcareous and porous. This excuse 

 can, however, scarcely be offered for the statement in the 

 concluding paragraph of the paper, that the '' arborescent " 

 forms in certain moss-agates are " as much like organic re- 

 mains as the so-called Eozoon is remote from such resem- 

 blance," — a statement difficult to understand, whether we 

 consider the essential dissimilarity of Eozoon to any moss- 

 agates, or the fact that, while most moss-agates show merely 

 dendritic crystallizations, others contain true vegetable or- 

 ganisms. 



As I have in my possession at present a considerable num- 

 ber of duplicate specimens of Stromatopora^ in such a state of 

 preservation as to show under the microscope their actual 

 structure, I shall be happy to send by mail chippings of these 

 specimens to any naturalists desirous of studying them and 

 of comparing them with such organisms as Loftusia on the 

 one hand or Eozoon on the other, with both of which the 

 Stromatoporce have decided affinities. I am sorry that I have 

 not material at command to supply specimens of the genera 

 Coenostromaj Caunopora., Syringostroma^ or Dictyostroma in 

 such states of preservation as to show their structures advan- 

 tageously. 



Montreal, May 15, 1878. 



IV. — Notes on Carboniferous Mollusca. By R. Etheridge, 

 Jun., F.G.S. 



[Plate I.] 



1. On the Hinge-structure and Generic Affinity of Pecten 

 Sowerbii, J/'Coy. 



When last I had occasion to refer* to this common and 

 characteristic Carboniferous shell, I called attention, amongst 

 other things, to the late Mr. Meek's remarks on its probable 

 identity with Pecten aviculatus, Swallow. The peculiar 

 hinge-structure of the latter, combined with that of P. demissus, 

 Phill., of the European Oolitic rocks, afforded Mr. Meek the 

 data for the diagnosis of his genus Entolium. With the excep- 

 tion of the central cartilage-pit f, the hinge-structure of our 

 * Geol. Mag. dec. 2, iv. p. 241. f Ibid. dec. 2, i. p. 302. 



