480 WELLBURN : ox THE (iENUS CCELACANTHUS. 
it was of large size, extending from a point immediately posterior to 
the pectoral fins to a point a short distance anterior to the anal fin. 
It sometimes shows a single anterior aperture, by which its internal 
cavity communicated with the oesophagus. Its walls are formed of 
a longitudinal series of large, imbricating, bony laminae, composed 
of superposed lamellae. The inner face exhibits (as pointed out by 
Von Zittel), and as shown by specimens in the author's collection, 
a large reticulating rugae, very similar to the network (made known 
by Owen) in the lung-like air-bladder of the recent fish Polypteriis, 
and it appears to the writer to be highly probable that the air-bladder 
of Coelacanthus played a similar, if not identical, part in the economy 
of the fossil fish to that played by the lung-like air-bladder of the recent 
fish, and this seems to be rendered more certain when we study the 
life-history of the fishes, as both seem to have thrived best, and to 
have been most plentiful under the same muddy surroundings ; 
again it appears likely that the air-bladder of Coelacanthus, as well as 
Polijpterus, was able, under certain dried-up conditions, to perform 
for the time being the functions of a lung. 
Distribution and Range. 
Coelacanthus has a very wide distribution in the Yorkshire Coal 
Measures, being found in nearly all the fish-bearing localities ; in 
fact, it is by far the most characteristic fish in these Measures. It 
has a range from the Halifax Soft Bed Coal at the base of the Lower 
Coal Measures to the Stanley Scale Coal, one of the uppermost beds 
in the Middle Measures, i.e., to one of the uppermost coal seams 
found in Yorkshire. 
Remarks. 
The vast number of specimens which have enabled the writer 
to complete the restoration have been mainly found in the cannel 
coal, at Tingley, near Leeds, where the fish was, until quite recently, 
found in great abundance and perfection, but now, unfortunately, 
ow'ng to the non-working of the cannel coal in this locality, specimens 
are not to be found. 
Another point may be mentioned here, viz., that the Yorkshire 
Measures have yielded eleven different species (see table of distribution), 
