304 Miscellanea. 



has suggested to me that the cylindrical fossil might be considered 

 a stem, the axis being the pith, the radiating divisional lines the 

 medullary rays, and the intervening cuneiform masses the wedges 

 of wood. I have carefully considered this opinion, but find it 

 impossible to adopt it, from the ease with which the transverse 

 fractures take place, and the perfection of the surfaces produced ; 

 as it is obvious that such numerous and perfect divisional planes, 

 as we observe at right angles to the axis, would be incom- 

 patible with the above view. On the whole, after a careful study 

 of the specimens at my disposal, T feel disposed to view the genus 

 as closely allied to Sphenophijllum, in which we have a jointed stem 

 surrounded by verticillate whorls of from six to twelve wedge- 

 shaped leaves with dichotomous veins ; and in this light J^ertebraria 

 becomes intelligible, for I have clearly ascertained the existence of 

 the dichotomous neuration on each of the wedge-shaped divisions 

 of the transverse planes, which will, according to this view, repre- 

 sent the surface of a whorl of verticillate leaves ; and we may 

 consider therefore the main difference between Sphenophi/llum and 

 Vertehraria to consist in the greater approximation of the whorls 

 of leaves in the latter, the internodes being so very short that the 

 whorls of leaves are brought in contact, or nearly so. I might 

 therefore provisionally characterize 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 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 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 Sphenophyllurn these may 

 have been fresh-water 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 characterize our species as follows : — 



Vertehraria australis (M'Coy). PI. IX. fig. 1. 



Sp. Char. Leaves constantly eight in each whorl. 



The fragments are of various lengths, but with a pretty uniform 

 diameter of about seven lines. Tlie 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, 



