354 SYRINGODENDRON. 



The vertical position of these trunks, however, is only 

 occasional and accidental ; they lie inclined at all degrees 

 throughout all the strata of the carboniferous series ; but are 

 most frequently prostrate, and parallel to the lines of strati- 

 fication, and, in this position are usually compressed. When 

 erect, or highly inclined, they retain their natural shape, and 

 their interior is filled with sand or clay, often different from 

 that of the stratum in which their lower parts are fixed, and 

 mixed with small fragments of various other plants. As 

 this foreign matter has thus entirely filled the interior of these 

 trunks, it follows that they must have been without any trans- 

 verse dissepiments, and hollow throughout, at the time when 

 the sand, and mud, and fragments of other plants found 

 admission to their interior. The bark, which alone remains, 

 and has been converted into coal, probably surrounded an 

 axis composed of soft and perishable pulpy matter, like the 

 fleshy interior of stems of living Cactese ; and the decay 

 of this soft internal trunk, whilst the stems were floating in 

 the water, probably made room for the introduction of the 

 sand and clay. 



These trunks usually vary from half a foot to three feet 

 in diameter. When perfect, the height of many of them 

 must have been fifty or sixty feet, at least.* 



Coal formation, and infers from this fact that they grew on the spot where 

 tlicy are now found. M. Constant Provost justly objects to this inference, 

 that, had they grown on the spot, they would all have been rooted in the 

 same stratum, and not have had their bases in different strata. When I 

 visited these quarries in 1826, there were other trunks, more numerous 

 than the upright ones, inclined in various directions, 



I have seen but one example, viz. that of Balgray quarry, three miles N. 

 of Glasgow, of erect stumps of large trees fixed by their roots in sand-stone 

 of the coal formation, in which, when soft, they appear to have grown, close 

 to one another. See Lond. and Edin. Phil. Mag. Dec. 1835, p. 487. 



* M. Ad. Brongniart found in a coal mine in Westphalia near Essen, 

 the compressed stem of a Sigillaria laid horizontally, to the length of forty 

 feet" it was about twelve inches in diameter at its lower, and six inches 

 at its upper extremity, where it divided into two parts, each four inclics- 



