. 
ERECT SIGILLARIA. 127 
carbonized bark. All the stems were filled with blue clay, 
or shale, a proof that they were hollow when submerged in 
the mud, which is now consolidated into the shale in which 
they are imbedded. But it is not probable that they were 
My 
fb 
originally tubular, like a reed: on the contrary, there is 
evidence to show that they were highly organized. Their 
internal structure may have decayed, or been destroyed by 
insects or other depredators ; as is often the case in tropical 
climates, where the trunks of timber trees are speedily 
excavated after their fall, and afford shelter to innumerable 
insects and reptiles, as the weary traveller often finds to his 
surprise and annoyance.* The late Mr. Bowman affirmed f 
that these trees were dicotyledonous, and stated that medul- 
lary rays and coniferous structure could be detected ; an 
opinion, which the researches of M. Brongniart on the Sigil- 
larize have fully corroborated. 
Many other instances have been noticed of Sigillariz 
standing more or less erect in the strata. In forming the 
railway tunnel at Claycross, five miles south of Chesterfield, 
through the middle portion of the Derbyshire coal measures, 
in 1838, a group of nearly forty trees (Sigillarie) was dis- 
_ covered, standing not more than three or four feet apart, at 
right angles to the plane of the strata.{ On the coast of 
Northumberland, within the length of half a mile, twenty 
trees were observed by Mr. Trevelyan, in 1816 (Ld. p. 470). 
The coal-pit at St. Etienne, in France, described by M. Alex. 
Brongniart, is celebrated for affording an example of this 
_ phenomenon (Wond. p. 673) ; but the positions of many of 
those stems are inclined at various angles, and their roots 
implanted in different beds, so that the perpendicularity of 
the erect trees is probably accidental (Bd. p. 471). 
The most remarkable instance hitherto observed, is on the 
* Mr. Hawkshaw, Geol. Proc. p. 269. + Geol. Proce. vol. iii. p. 270. 
+ Ibid. p. 272. 
