The Coal of Australia. 
431 
being so very short that the whorls of leaves are brought in 
contact, or nearly so. I might therefore provisionally characterise 
the genus as follows :— 
Gen. Char. Stem slender, surrounded by densely aggregated 
whorls of verticillate, cuneiform leaves, having a dichotomous 
neuration. 
To the above 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 appearance 
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 distances of about a line from each other, 
the latter having only a small definite number depending on 
the number of leaves in a whorl. The leaves themselves are flat, 
rather thick, dilated at the tip in such proportion that there is no 
space left between the edges of the adjacent leaves. 
It is very possible that together with Sphenophyllum these may 
have been freshwater aquatic plants allied to the recent Marsilea, 
in which we see a quaternary arrangement of cuneiform leaves 
with dichotomous veins, but the affinity is not very strong. The 
Australian species seems distinct from either of those occurring in 
the Indian beds, by the smaller number of leaves in the whorl, 
which is perfectly constant in all the examples I have seen. I 
would propose to name and characterise our species as follows :— 
Vertebraria australis (M’Coy). 
Sp. Char. Leaves constantly eight in each whorl. 
The fragments are of various lengths, but with a pretty uni¬ 
form diameter of about seven lines. The radiating dichotomous 
veins are never strongly marked, apparently from the original 
softness of the texture of the leaf; in many cases we observe 
between them an obsolete concentric plication, probably from the 
same cause, and which may explain the nature of certain vertical 
striae visible on the perpendicular fracture, crossing the horizontal 
lines which mark the edges of the leaves. 
VOI.. III. no. vi. 2 D 
