Benson.—Mazocarpon or the Structural Sigillariostrohus. 575 
the cone-scale, i.e. the cone-scale scar or bract scar, measures only one 
millemetre across. This small area is largely occupied by parichnos strands 
which accompany the trace and render the attachment very fragile. A 
great tendency existed for the cone-scales to separate from the cone-axis. 
Even the relatively perfect sporophyll cut radially (see Fig. 18) had become 
detached though scarcely displaced. 
In the upper part of the cone where the cone-scales are barren or 
immature they are found attached. These facts point strongly to the con¬ 
clusion that the sporophylls of Mazocarpon were exceptionally caducous. 
Mr. Lomax informed me, on inquiry soon after the delivery of the speci¬ 
mens, that the sections in the series 537, 1-9, ‘ may be taken as on an 
average half an inch apart ’. As two of these are in the peduncular region 
(527, 1 and 2, see Fig. 10) this estimate, if correct, would justify us in 
regarding the cone as having measured between three and four inches in 
length. It may have been somewhat longer, as the stele, in the ninth and 
last available member of the series, is still giving off leaf-traces. 
The width of the cone can be obtained approximately by doubling the 
radial length of the sporophyll and adding the diameter of axis. As the 
radial section (Fig. 18) measures a little over 5 mm. and the axis (Fig. 20) 
is 3 mm. we may regard 13 mm. as a little under the width of the cone 
before it broke up. The upturned and laterally expanded parts of the 
sporophyll, which appear to have extended to the third in rank above 
(triple layers being seen in the transverse sections (527, 5 and 7)), must have 
also added to the thickness of the cone, which we may safely conclude could 
not have been less than 13*5 mm. in diameter. 
The anatomy of the Cone-axis , &e. All the tissues are primary. The 
cortex is differentiated into the usual mechanical outer region and the 
lacunar middle cortex, which is often fairly well preserved. The stele is 
circular in section, medullated, and shows projecting protoxylem groups. 
The sporophyll traces are mesarch and pass out through the outer cortex 
accompanied by a trough-shaped parichnos strand. The leaf-trace is 
undivided throughout and travels in the pedicel of the sporange and not in 
the keel or dorsal midrib of the sporophyll. It can be detected with 
difficulty in the distal upturned part of the lamina (see next section). 
Section.V. The Sporophyll or Bract . 
The bract supporting the megasporange has been met with oftener and 
in better preservation than that of the microsporange, which appears in 
Figs. 12 and 13 as a curiously inadequate structure to support the bulky 
microsporange. 
The following description is therefore based on the megasporangial 
bract. 
