88 Sakni. — On an Australian Specimen of Clepsydropsis. 
of the tracheides. Only those parts are shown in solid black where outlines 
of tracheides were recognized with tolerable certainty. The dotted areas 
refer to parts where the existence of xylem was only inferred. 
The shape of the trace at once decides the specific distinctness of the 
plant from either C. antiqua , Ung., or C. kirgisica , Stenz. It is proportion- 
ately thinner, has pointed instead of truncated ends, and the internal 
contour of the peripheral loops is fusiform instead of elliptical. 
The tissue filling the peripheral loops, which in the Barraba fossil 
consists of parenchyma intermixed with small tracheides, is not preserved 
at all. The loops are instead filled up by a deposit of mineral granules in 
the form of peculiar branched tubular structures, the appearance of which ' 
suggests that they were probably formed in the same manner as a continu- 
ally growing semi-permeable membrane round a crystal of copper sulphate 
in a solution of potassium ferrocyanide. A similar process was probably 
responsible for a pseudo-cellular structure replacing the cortical cells in 
some of the leaves, each pseudo-cell having been formed round an inde- 
pendent centre. 
The tracheides are practically all scalariform (PI. IV, Fig. 4), with 
occasional anastomoses between the bars of thickening, as an approach to 
the reticulate type. The peripheral loops are lined with tracheides 
distinctly narrower than those immediately outside them. As we pass still 
farther away from the loops the tracheides again diminish in size (PL IV, 
Fig- 5 )- Only one spiral element was observed ; of the others some on 
account of their small diameter gave the impression of being annular. In 
a few scalariform tracheides the pits, which were rather farther apart than 
usual, showed in surface view what may be called 4 false borders ’, because in 
sectional views they could not be seen at all. It may be that the free edges 
of the thickening bars, instead of hanging over the pit so as to narrow the 
entrance to it, sloped in the opposite direction, so that the entrance to the 
pit became wider than the bottom. The effect in surface view would in 
either case be almost the same. The tracheides average about 100 /x in 
diameter ; the largest seen was 180 /x, the smallest 20 /x across. 
In one of the leaf- traces the inner ends of the two peripheral loops 
were connected by a series of narrower tracheides similar in size and form 
of pitting to those lining the loops themselves (PI. IV, Figs. 6, 7). The 
significance of this feature has already been explained on p. 84. 
Dr. Bertrand (1911 c, p. 509) records the presence in the leaf-strand 
of C. antiqua of a number of tracheides of secondary origin. No trace of 
secondary xylem was present in any of the leaf-strands of the Mt. Tangorin 
fossil. 
The origin of the pinna-trace is exactly as in C. antiqua , that is, the 
trace is constricted off as a closed ring from the end of the peripheral loop. 
Unfortunately the large number of intrusions have greatly disturbed the 
