BY THE REV. J. E. TENISON-WOODS, F.G.S., F.L.S. 77 



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 top 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." 



Prof. M'Coy considered that the Australian specimens were 

 distinct from either of those figured by Prof. Royle, and he named 

 them Vertebraria australis, giving the following diagnosis : — 

 "Leaves constantly eight in each whorl." He adds that the 

 fragments were of various lengths, with a pretty uniform 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." 



This ingenious explanation of the nature of Vertebraria, did not 

 meet with general acceptation. Not only was there no analogy 

 for anything like these cylindrical masses of leaves, but the 

 divisions themselves did not resemble any known leaf. 



Prof. Dana confessed his inability to suggest any explanation of 

 these singular forms. He says : "we do not pretend to understand 

 their nature, or explain by any hypothesis, their structure. They 

 are broad linear, three-eighths to seven-eighths of an inch wide, with 

 the sides parallel, and from the appearance of the fossil, it is 

 apparent that they must have been hollow, as remains of both an 

 upper and an under integument can be distinguished. They 

 consist of two unsymmetrical longitudinal halves, In one 

 specimen, each half has a transverse elevation at distant intervals, 

 and between these elevations, a transverse depression. The 

 elevations and depressions are unlike in their length of interval 

 in the two halves. In another specimen the structure is different, 



