DAVIS: FISH-REMAINS IN THE COAL-MEASURES. 47 
the vertical series, there is a stratum which contains fossil fish. 
The fish beds are generally of small extent, often less than 
one inch, rarely exceeding a few inches in thickness. The 
fish remains have been found in several instances in the 
Lower Coal Measures, as well as those higher in the series ; 
notably above the Better Bed and Black Bed Coals in the 
Lower, and the Middleton Main Coal, the Yard Coal, and the 
Stone Coal in the Upper Measures. That the fish will be 
found to occur above other beds of coal, when due search 
shall have been made, appears very probable ; they have not 
been recorded hitherto, because there has been no one 
sufficiently interested to make the necessary observations. 
The fish remains belong to the Elasmobranchii and the 
Ganoidei ; the latter very much prevailing both in point of 
numbers and frequency of occurrence. 
One section of the Ganoids existing at the present time, 
represented by Lepidosteus, Amia, and Calamoichthys, are 
all fresh-water species, living in the rivers of Africa and 
America. Another large group, the Sturgeons, are denizens 
of alternately fresh, brackish, or salt water. The Ganoids of 
the Coal Period, represented by Megalichthys, Palceoniscus, 
Acrolepis, Platysomus, and Holoptychius, were probably more 
nearly allied to the fresh- water group than to the sturgeons ; 
and it is a fair inference that they were fresh- water species. 
The Elasmobranchii, consisting of the sharks and Rays, 
are generally found inhabiting salt water, and are essentially 
marine groups. There are, however, several instances on 
record in which they live in fresh water. Amongst others, 
they are said by Mr. T. Belt,* whose lamented death occurred 
so short a time ago, to occur frequently in the Lake of 
Nicaragua, in Central America ; and they are common in some 
large rivers, such as the Ganges. If the instance cited by 
* "Naturalist in Nicaragua," by Thomas Belt, F.G.S., &c. 
