74 J^Ji^ American Geologist. February, is99 
p. 525), but not yet in print, I adduced a mass of facts in sup- 
port of a theory that coal-beds, as a rule, have not suffered 
anything- like so much compression or reduction in original 
thickness as many writers on coal-formation have claimed — 
an ultimate thinning or vertical squeezing down to 1-5 to 1-12 
of their original thickness; or which is the same thing, coal 
beds are said to have been from five to twelve times as thick 
as soon as completed or covered up by mud, sand, etc., as 
we have them today. In the light of this phenomenon of par- 
tial solidification during accumulation, and the resin-soaked 
aspect of coal, generally, the above teaching will have to be 
modified somewhat in future text-books. 
4. The literature of coal-formation, so far as I know it. 
is most unsatisfactory relative to the probable or supposed 
nature and vegetable structure of the pitcli-coal layers or la- 
minae, that give coal its "grain" or stratified aspect (so-called). 
How exceedingly variable in size and shape these black lines 
or plates are, all observers of coal-beds know. Looking up 
the opinions of authors as to the meaning of these laminae, 
I find that hardly any two agree, though most seem to favor 
a woody origin of some kind, rather than that they represent 
patches or streaks of residual products having little or no 
organic structure. I have givefi much attention of late to 
these black laminations, both in bituminous coals and in an- 
thracites; and, strange as it may seem, the latter have afforded 
the most favorable materials developing anatomical structures. 
Some of these tissues, etc., I purpose publishing in the near 
future. Now, these black laminae are by no means all black, 
nor uniform in lustre, or in possessing clearly-defined and 
flat exterior surfaces, terminals, etc. The edges of some are 
wavy, ragged, spiny, etc.; the upper and lower plates or lay- 
ers of some consist of closely-compacted rods, straight or 
twisted: or dense black in one layer while the parallel one is 
composed of rods. Other laminae consist wholly or largely 
of wavy vertical rows of alternating black and gray streaks or 
spots : others are of black layers interlaminated with gray dull- 
lustrous material, in which latter material a macrospore occa- 
sionally peeps out. There are numerous laminae wholly made 
up of flattened fibrous tubes, filled with as well as surrounded 
by gray granular material; the aspect of lines, etc., differing 
