660 



HISTORY OF THE VEGETABLE KINGDOM. 



merous soars are situated between the furrows, 

 arranged in rows. The specimens are generally 

 found in two states: ]st. With the bark entire, 

 in which case the scars are clean, broad, and well 

 defined; 2d. Where the bark has been destroyed, 

 and nothing is seen but the passage through 

 which the vessels of the leaf communicated with 

 the stem. In these latter, the scars are narrow, 

 small, indistinct, and often double. 



Large portions of these stems are frequently 

 found lying across the strata, having escaped 

 compression, with roots proceeding from them 

 on all sides. They are generally surrounded by 

 a coating of coal about an inch in thickness. 

 The longitudinal flutings with the scars are often 

 awanting, or very indistinct, on the lower or 

 root portions of the larger stems. The stem has 

 been originally hollow, and in the fossil state 

 is fiUed with sandstone, very generally of a dif- 

 ferent kind from that of the enveloping strata, 

 a proof that these plants have been drifted from 



Shall 



a Sigillana pacliydermn. h Branched fragraejit of root. 



a different locality. The wood cut represents 

 one of these fossils found immediately above 

 the coal in Killingworth colliery, near New- 

 castle.* The lower part was two feet in dia- 

 jiieter, coated with coal, and indistinctly fluted; 

 the roots were imbedded in shale, and could be 

 traced four feet or more from the stem, branch- 

 ing, and gradually growing less. Fig. J repre- 

 sents one of the larger roots. These roots, as 

 well as the whole of the stem, were composed 

 of fine grained white sandstone, totally different 

 from the rock in which the lower portion of the 

 fossil was enveloped, but agreeing perfectly with 

 a bed surrounding the higher part. At the 

 height of about ten feet, the stem was partially 

 broken and bent over, so as to become horizon- 

 tal; and here it was considerably distended late- 

 rally, and not more than an inch thick, having 

 the flutings comparatively distinct. This stem 

 formed one of a considerable group, not less than 

 thii-ty being visible within an area of fifty yards 



* Lindlcy and Hutton's Fossil Flora, Vul. I. 



square, some of them larger than this individual, 

 all presenting the same general characters ; and 

 the perpendicular trunks of this fossil are often 

 the cause of serious accidents to the colliers, as 

 the coally envelope weakens the cohesion of 

 the strata, causes them to detach themselves, 

 and suddenly slip out of the roof after the seam 

 of coal has been removed from below, when they 

 leave large circular holes, sometimes four to five 

 feet in diameter. M. Brongniart describes a 

 stem which he traced in the strata of the coal 

 mines of Kunzwerk, near Essen, as extending 

 along the line of the strata for forty feet, its dia- 

 meter gradually decreasing towards the top, when 

 it branched out into two, each branch being about 

 four inches in diameter. Some have associated 

 the sigillarias with the tree ferns, others with 

 the caoteE. From the sigillaria having a true 

 and distinct bark, they are in all probability 

 dicotyledonous. 



There are several species; sigillaria pachyder- 

 ma. S. alternans, with a double row of approxi- 

 mated oval scars, each with a smaller scar in the 

 centre. S. reniformis, with roundish kidney- 

 shaped or double approximated scars, with a 

 point in the centre. 8. catcnulata, with oval 

 scars, united at the ends, forming a sort of chain. 

 S. oculata, with large oval scars, and an eye iu 

 the centre. 



Calamites. These; which are also abundant 

 in the coal strata, appear to have been branch- 

 ing plants, with hollow stems, and a distinctly 

 separated wood and bark, often many feet in 

 length, and readilyseparatingat their joints. The 

 whole substance appears to have been very soft 

 and reed-like, so as to be easily compressed, the 

 internal cavities at the joints most probably sup- 

 ported by horizontal partitions. The surface of 

 the stems was marked with numerous parallel 

 furrows, converging in pairs towards the joints, 



a Ciilamites mug:eotii. 



h Partition of a joint. 



and then turning abruptly inwards. They were 

 branching plants, as the figure above shows. 



