Bivalve Shells of Nova Scotia. 119 



and another referred to the same group has since been 

 found to belong to the genus Anthracosia or Carbonicola. 



Before the publication of the second edition of "Acadian 

 Geology " in 1868, I had sent specimens to my friend, the 

 late Mr. Salter, of the Geological Survey of Great Britain, 

 who was at the time studying the British species, and he 

 described them with some other fossils from Nova Scotia 

 which I had placed in his hands, in a paper in the Journal 

 of the Geological Society 1 with figures of three of the species, 

 which he referred to his two new genera Anthracoptera 

 and Anthracomya, then recently established for the British 

 species. He thus dropped my genus " Naiadites " and 

 substituted two other names of later date. I might have 

 objected to this, but I have made it a rule never to raise 

 questions of priority or of mere nomenclature, and I felt 

 quite sure that Salter was not a man to do any injustice, 

 while I fully recognized his superiority as an authority on 

 fossils of this kind. There was, however, a more important 

 point involved, having relation to the whole question of the 

 conditions of accumulation of coal. Salter held the shells 

 to be probably marine, and on this ground my name 

 Naiadites was objectionable to him, while one of his names-, 

 Anthracomya, implied the idea of burrowing creatures allied 

 to the Mya or sand clam. Now, throughout the whole 

 thickness of the coal-formation of Nova Scotia, there is an 

 entire absence of the species of marine mollusks found in 

 the underlying marine limestones, while the bivalve shells 

 in question occur almost exclusively in the coal measures 

 and are not found in the admittedly marine beds. The 

 question was an important one with reference to the mode 

 of accumulation of coal, a subject then engaging my atten- 

 tion ; for though the occurrence of a few exceptional beds 

 holding marine shells might be explicable as the result of 

 occasional invasions of the sea on beds usually beyond its 

 reach, the association of these shells with the beds of coal 

 was so constant and intimate that if they could be proved 

 to be marine, a similar conclusion might - naturally be 



1 Vol. XIX, p. 80, 1863. 



