cash: fossil fructifications of YORKSHIRE COAL MEASURES. 441 
a rich and varied assortment of marine fossil shells, such as 
Goniatites, Nautili, Orthocerata, Aviculopecten and others, along 
with a few fish remains. Immediately underlying these marine strata 
is the Hard Bed Coal, containing in many places (for they are not 
uniformly distributed), those remarkable calcareous nodules locally 
known as coal-balls. The coal-balls are found in the coal itself, and in 
some places the whole bed is occupied by them with only a little 
admixture of coal, but generally they seem to be scattered throughout 
the coal seam at irregular intervals. Some coal pits yield them 
more abundantly than others. 
The material composing the coal-balls consists of a mixture of 
carbonate of Hme and carbonate of iron, with iron pyrites, calcspar, and 
fossilised vegetable remains. They are nearly always thickly coated 
with pyrites, and are often very difficult to break open, an ordinary 
hammer being of little use for this purpose, and too frequently the 
whole ball is one mass of pyrites. In composition and external 
appearance they somewhat resemble the nodular concretions which 
occur in the marine strata above the coal, but there is a total 
difference in their fossil contents. The " Coal-balls " contain fossil 
plants exclusively, while the baumpots " contain marine shells, and 
sometimes fish-remains, and occasionally fragments of fossil-wood 
(Dadoxylon), which have evidently drifted into the sea or estuary in 
which the bed was originally laid down from some neighbouring land. 
The hard bed coal rests upon the very peculiar rock called 
ganister, which varies in thickness from 1 foot 4 inches in the 
neighbourhood of Halifax, to 3 feet in the neighbourhood of 
Penistone. Underlying the ganister there is a bed of soft earth, 
and both seat earth and ganister are full of Stigmarian roots and 
rootlets, while some of the best specimens of the ordinary Stigmariae 
are met with in the ganister rock About 75 feet below the hard 
bed coal the soft bed coal is met with, and midway between them 
occurs another thin seam called the middle band coal ; underlying it, 
there is a valuable bed of fire-clay, which is extensively worked in 
this district. Midway between the middle-band and the soft bed 
coal, there are three layers of shale, which are literally full of 
Anthracosia, separated by black shale containing Spirorbis carbonarius. 
