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on the fish fauna of the yorkshire coal measures, 
by edgar d. wellburn, l.r.c.p., f.g.s., f.r.i. p.h., etc. 
Introduction. 
In Yorkshire only the Lower and Middle Coal Measures are 
present, the Upper being absent.'"^ On the north and west the coal- 
field is bounded by the Millstone Grits; on the east they sink below 
the Permian Limestones, and on the south — through the Barnsley 
beds — they become continuous with the Derbyshire coalfields. 
The Lower Coal^ Measures extend from the Rough Rock 
(Millstone Grits) at the base to the Silkstone or Blocking Coal 
at the top, and are composed of thick-bedded, often coarse, grit 
rocks, with thick intermediate beds of shales, with occasional 
seams of coal. That some of these coal seams were laid down 
under marine conditions (estuarine) is certain, and especially is 
this the case of the Halifax Hard Bed Coal, where fish remains 
are associated with a distinct marine fauna consisting of Goniatites, 
Orthoceras, Aviculopecten, Posidonomya^ kc. Higher in the series 
fresh water conditions appear to have prevailed, the measures 
being of the Lagoon type, the shales not only yielding fish 
remains, but also a good assortment of land plants and fresh water 
mollusca, and occasionally remains of Lahyrinthodonts are found. 
The Middle Coal Measures consist of rapidly alternating 
.shales and sandstones, with frequent recurring coals. These 
measures were in all probability laid down in a series of lagoons 
or lake basins, and appear to have been of fresh water origin. 
Several of the seams have 34elded fish remains, and one — the 
Cannel at Tingley, near Leeds — contains a most remarkable series 
of fish, many of the specimens being in a nearly perfect condition, 
whereas in the other coal shales — both in the Middle and Lower 
Measures — the fish remains are only found in a very fragmentary 
condition. 
* Prof. Green gives some measures in the Conisborough district as probably 
belonging to the Upper Coal Measures (see Geology of the Y'orkshire Coal 
Fields). 
