DAVIS : DISTRIBUTION OF FOSSIL FISHES. 
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Pleuracanthus (including Orthacantkus Ag, Diplodus Ag, and 
Xenacantbus, Beyr) forms a large group and is distributed over 
the whole series of the coal measures. Several new species have 
been found in addition to the loevissinius, cylindricus, and gibbcsus 
of Agassiz. The whole series of about a dozen species is ex- 
tremely interesting for many reasons which cannot be entered into 
at present. Acanthodes and Lcpracanthus occur in the lower coal 
measures in the Bone-bed above the better-bed coal, and are not 
very rare, tloplonchus and Phricacanthus, new genera, are also 
from the same bed. Several teeth which are supposed to have 
belonged to Elasmobranch fishes, as Cladodus, Ctenoptychius, 
Petalodus, Poecilodus, and Ilelodus occur in some of the strata. 
Coinpsacanthus, a genus of fish, instituted by Dr. Newberry in 
the United States, with only one row of denticles along the dorsal 
surface, and hitherto unknown in this country, is now represented 
by two species from the cannel coal. To the genus Fleurodus, 
named but not described by Professor Agassiz, the Yorkshire coal 
measures have rendered specimens affording information on which 
to base not only a description of the teeth, but also of the spines. 
The fish was probably nine or ten inches loug, very deep in the 
body, with a large gape and pavement-like teeth. At the highest 
point of the dorsal part of the fish a smooth spine was implanted, 
broad at the base but rapidly tapering to a point, and from two to 
three inches in length. The whole of the fish was cartilaginous. 
One or two comparisons of the fish-fauna of the Yorkshire 
coal-field with those of other parts of the country may perhaps be 
useful. The principal supplies of fossil fish have hitherto been 
derived from the Scotch coal measures at Burdie House and Gil- 
merton ; from Newsham, near Newcastle-on-Tyne (Low Main 
Coal-seam) ; from the Ironstone Shales of North Staffordshire, and 
from the coal measures of the West Riding of Yorkshire. Several 
of the Lancashire beds have yielded fish remains, notably the 
Arley mine, but not in such numbers or of sufficient diversity to 
render them of peculiar interest. Considered in relation to the 
other sources mentioned, the Yorkshire fossils are peculiar for the 
