Geological Society. 387 
than in monocotyledonous vegetation, excluding necessarily those 
always hollow; and he does not remember to have seen a single in- 
stance of a palm similarly acted upon. Sometimes the portion of the 
dicotyledonous tree remaining on the ground, presented very much 
the appearance of the founder’s mould, when the pattern has been 
withdrawn from the sand, and before the metal has been run in; 
and by this kind of decay, a cavity is formed from which a fac simile 
of the tree might be cast. In other cases, prostrated trunks having 
the appearance of being solid, have yielded to the pressure of his 
feet, and proved to be only hollow tubes. Dangerous accidents have 
also occurred from temporary bridges constructed of dicotyledonous 
trees having given way beneath the passenger, though there was 
no outward indication of decay. The bark of these trees had 
changed but little, though nothing of the interior remained but 
dust, and a few remnants which crumbled beneath the slightest 
touch. 
The low and flat tracts in which this destructive operation goes 
on most rapidly, are those in which, from the deep rich soil and 
excessive moisture, all below the tall forest trees and larger palms 
is occupied by canes, bamboos, and minor palms. Such tracts would 
be most easily submerged; and in Mr. Hawkshaw’s opinion they 
might hereafter present a seam of coal, which would afford but few 
distinct traces of palms and forest trees. These phzenomena, he says, 
may explain in part, why so few distinct forms remain of the num- 
berless forest trees, which must have formed a portion of the vege- 
table kingdom, at the time of the accumulation of our coal deposits. 
Mr. Hawkshaw does not attempt to explain the process by which 
dicotyledonous trees are rendered hollow in tropical forests. He 
expresses doubts respecting the probable nature of the Calamites 
of the coal measures, and offers no explanation of the means by 
which they have been preserved in so great abundance. If the coal 
be considered as the debris of a forest, he says, it is difficult to ac- 
count for not finding more trunks of trees than have been discovered 
in our coal basins; and he observes, it is only perhaps by allowing 
the original of our coal seams to have been a combination of vege- 
table matter, analogous to peat, that the difficulty can be solved. 
In this case, he is of opinion, but a few isolated trees might be ex- 
pected to be found, and that the remains of vegetable forms most 
frequently discovered, would only be confirmative of the antiseptic 
qualities of their original nature, as previously advanced by Professor 
Lindley, and not of the number or importance of their particular 
genera at the time of their deposit. 
In conclusion, Mr. Hawkshaw says, that whatever opinion may 
be drawn from what is conjectural in his paper, it will be obvious, 
that though fossil remains may be found filled with a mechanical 
deposit, and containing traces of other vegetables, yet that this con- 
dition does not prove, that the plants were originally hollow, nor 
even render it the most likely hypothesis, as they may have been 
hard wood-trees, the centre of which had been removed by natural 
processes. 
