52 The Americati Geologist. July, 1900 
specimens of this plant-fragment; some being less pronounced 
than others. Whichever way the specimens are broken trans- 
versely, the same, or apparently the same, cellular structures 
and tooth-shaped exteriors are observed, and no other kind of 
tissue has been recognized in these zones a a'. The ground 
mass of the coal — the matrix in which those particular fossils 
are embedded, seems to consist chiefly of small detrital plant 
remains in the shape of black streaks and patches, with macro- 
spores here and there, in a dark gray granular material which 
seems to be impregnated by (?) amberite, or clear, solidified ? 
petroleum. 
As to the true character or determination of this form ; at 
first sight it might be taken for the flattened or compressed 
woody wedgs (exylem) of the calamite, the sigillaria, the stig- 
maria or some other coal-measure plant: but to the author, 
there seem to be several reasons why this cannot be so, name- 
ly: The specimens fail to reveal any suggestion of the thin 
edges or apices of the woody wedges, in fact the very regular 
structures existing along such a horizon is the reverse of what 
such flattened wedges would show. Secondly. Instead of 
gaps or openings in the outer margins of the layers a a' which 
give to the specimens the tooth-shaped aspect, these could not 
have formed, there would have been a crowding instead of a 
stretching of the material in this position. Thirdly. No med- 
ullary rays or other cross-graining is present, and the tout en- 
semble seems to suggest something quite different from the 
genera named in this connection. If these are or could repre- 
sent woody wedges, then the dense black central material 
would be fossilized pith, and pith, we believe, did not become 
mineralized into pitch-coal layers, but rather went to form 
much of the dull gray material of coal. Whatever this fossil 
really was, its mode of occurrence in the coal as well as its in- 
dividual peculiarities, here pointed out, seem to indicate that 
it is practically in place of growth, apparently reduced in bulk 
vertically as regards the central zones, but not materially com- 
pressed as to the outer zone a and a'. So far as has been deter- 
mined it is of the unicellular order or group. 
In a coal-bed in Michigan, the author has detected a speci- 
men of somewhat similar facies. 
