Geological Society. 



38? 



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 withdrawn from the sand, and before the metal has been run in ; 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 phenomena, 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. 



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