76 ON THE FOSSIL FLORA OF THE COAL DEPOSITS OF AUSTRALIA, 



The plants have the appearance of jointed stems, with generally 

 a line of division down the centre. The joints on each side of the 

 division do not correspond with one another, and they are very 

 irregular in size and shape. In transverse sections these stems 

 are cylindrical, and then the central division is seen to be one of 

 a series of radiate longitudinal partitions which divide the stem 

 into eight or nine cuneiform portions. • Prof. M'Coy stated that 

 it was suggested to him by an eminent botanist that the cylindrical 

 fossil might be considered a stem, the central axis being the pith, 

 aud the radiating divisional lines the medullary rays, and the 

 intervening cuneiform masses the wedges of wood. Prof. M'Coy 

 however would not accept this view, as he justly says from the 

 ease with which the fractures took place along these lines of 

 division, and the evenness of the surfaces produced. He noticed 

 also something like a fine neuration in the transverse wedge shaped 

 masses, showing clearly dichotomous veins. From these circum- 

 stances he was disposed to view the plant as closely allied to 

 Sphenophyllum, in which there is a jointed stem surrounded by 

 vertical whorls of six to eight wedge shaped leaves with dichoto- 

 mous veins. He thought that the main difference between 

 Sph&rvophyllwm and Vertebraria consisted in the greater approxi 

 mation of the whorls of leaves in the latter, the internodes being 

 so very short that the whorls of leaves are brought into contact, or 

 nearly so. He therefore provisionally defined the genus thus : — 

 " Stem slender, surrounded by densely aggregated whorls of ver- 

 ticillate cuneiform leaves, having a dichotomous neuration."* To 

 the above he continues '' we might add that the number of leaves 

 in a whorl depends on the species, and that from the whorls being 

 so close as nearly to touch each other, the fossils have the appear- 

 ance of lengthened cylinders, breaking readily in a horizontal and 

 vertical direction, the former coinciding with the surfaces of the 

 leaves, the latter coinciding with the vertical prolongations of the 

 lines separating the leaves of each whorl, the former producible in 

 indefinite number, at distance of about a line from each other ; 



* Loc. cit., p. 146. 



