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The chief points brought out in my observations are— 
Ist. That some English and American Coals originated from 
the same class of vegetation. 
2nd. Seams of coal do not consist of one continuous bed 
of the mineral; sometimes the mass is divided into distinct 
divisions by a stratum of clay, as in the Welsh “ Four Feet.” 
At other times the divisions are clearly defined, without clay 
partings, as instanced by the “Splint Coal” from Whitehill 
Colliery, near Edinburgh. 
drd. Where a seam is made up of more than one bed, in no 
case that I have examined have those beds been identical, in a 
structural point of view. 
4th. The dull lustrous layers in some coal may be said to 
be made up of vegetable spores and spore cases. In the bright 
layers, and in bright coals generally, spores are much less 
numerous; in these the material which I have termed hydro- 
carbon is the chief constituent, associated with vegetable tissue. 
I have never yet seen a seam built up entirely of spores and 
spore cases, though certain portions may be. 
A knowledge of the structure of coal has a practical value. 
The occurrence of certain vegetable remains endow the mineral 
with certain properties; therefore a knowledge of this enables 
experts to pronounce on a typical specimen submitted to them. 
For instance, I have made a series of chemical analyses of spore 
and non-sporous coal. I know the effect upon the mineral of 
the presence, or non-presence, or scanty presence of spore layers. 
A pocket lens enables me to detect these bodies if there, and I 
can thus base certain conclusions on what I see. The same with 
regard to the occurrence of hydrocarbon. This knowledge is 
especially useful where a rough opinion is needed, 
I now come to another important part of my subject, and it 
is one which is necessarily somewhat speculative: it is the 
relation and character of the coal-forming vegetation. Among 
those who have made the matter a special study is Mr 
CaRRUTHERS, and anything which falls from him deserves 
careful consideration. In 1865 he published* a paper “ On an 
* Geol. Mag., Vol. II, 1865, p. 433, 
