188 J. W. DAVIS ON FISH-SPINES FROM THE LOWER COAL-MEASURES, 
DIscussion. 
Prof. Duncan asked for further information as to the geological 
relations of the bed containing these remains, and the conditions 
under which the fish lived. 
Prof. Morrts also wished to learn what were the exact relations 
of this band of fish-bearing shale and the underlying spore-coal of 
the “ Better bed ” in the Carboniferous series. 
Mr. Davis, in reply, said that the fish-remains above the Better- 
bed coal are always extremely fragmentary and almost comminuted. 
Specimens any thing like perfect are very rare. He suggested that 
the coal, after having been formed on land, probably became the 
bed of a lake or an open shore-line. He remarked that this thin 
bed extended uniformly over a very considerable area. In reply 
to Prof. Morris he stated that the Geological Survey had adopted 
a different line of division between the Middle and Lower Coal- 
measures from that formerly suggested by Prof. Phillips. He 
pointed out that marine and freshwater species of fish appeared to 
coexist in the Carboniferous beds, and compared this with the 
analogous case of the Lake of Nicaragua, as described by the late 
Mr. Belt. Freshwater forms of sharks are not unknown in the 
Ganges and other rivers. 
