84 Salmi. — On an Australian Specimen of Clepsy dr apsis . 
features of both Clepsydropsis and Ankyropteris strongly suggests that 
these two genera should be united. This step was proposed in a recent 
paper, 1 and in the following pages the genus Clepsydropsis will be under- 
stood to include Ankyropteris. 
It is of some interest to find that this conclusion is fully corroborated 
by some photographs of C. antiqua , Ung., published by Dr. P. Bertrand in 
1911 (1911 a, PL II, Fig. 16 ; PL I, Pigs. 1, 2 + 3 and 4 + 5 ; also Bertrand, 
1912 , Fig. 21, p. 228). These figures show beyond doubt that the mode of 
leaf-trace origin in that species was essentially the same as that in the 
Barraba fossil, and that known for C. (Ank.) Grayi , Will., if we disregard 
the complications due to the presence of the axillary branch. (See Fig. 35, 
p. 244, in Progressus , 1912.) 
The figures in question are based upon a single specimen, discovered 
by Dr. Bertrand among Unger’s originals. The unusually small dimensions 
of the petiolar strand led him to conclude that it was probably either an 
abnormally thin petiole or a normal petiole sectioned in its distal region. 
Dr. Bertrand, however, evidently overlooked one rather important point in 
the figure, which shows that it undoubtedly represents a section across the 
basal region of a petiole. This is the presence, in the tangential plane, of 
a plate of narrow tracheides forming a bridge between the two peripheral 
loops and similar to the tracheides lining the loops themselves. The signifi- 
cance of this feature at once becomes apparent when we consider that the 
clepsydroid shape of the strand in the Barraba fossil is the result of the 
tangential flattening, followed by a median constriction, of a closed xylem 
ring lined internally by a zone of specially narrow tracheides. An exactly 
similar condition was observed in one of the petiolar strands in the 
Mt. Tangorin specimen, and is described below (p. 88; see Fig. 6, PL IV). 
Subsequently I learned from Mrs. Osborn that the same feature is visible in 
her specimen, and that it persists for a short distance from the leaf-base 
upwards. 
A diagnosis of the genus Clepsydropsis as extended in accordance with 
the above suggestion is given in my paper above referred to, along with 
other theoretical considerations. 
IV. Description. 
Gross features. When received the fossil was an almost semicircular 
slab about 3*5 cm. thick, with the diameter of the semicircle about 1 1 cm. 
long. The more or less flat upper and lower faces showed the cut ends of 
about a dozen cylindrical petioles varying in diameter from about 15 to 
17 mm., a few of which were evidently compressed into unnatural shapes. 
The spaces between the petioles were packed with numerous occasionally 
branched roots running in all directions. These were possibly mixed with 
1 Sahni (1918). 
