533 
Daft. — Pityosirobus macrocephahts , L. and /ft 
The breadth of the scale increases gradually from the base upwards, 
being about i cm. near the apophysis. Carruthers gives a fairly good 
restoration of the scale of P» macrocephaliis ( 2 , PL XXI, Fig. 6 ), but his 
figure seems to show too great a contrast between the breadth of the 
apophysis and the rest of the vertical portion. Carruthers also describes 
a striking feature which he says is peculiar to P. inacrocephalus and P. 
ovatus , viz. that the basal scales are larger than those of the body. This 
is not found in any recent Abietinean cone. He says further, ‘ The basal 
scales are barren and the apophyses arise from their whole surface ; in 
the series immediately above them there is a short flat body to the scale, 
but the greater portion of the scale is covered with the apophysis ; the third 
series are fertile and have a larger and more ascending body ’. Mr. Gardner 
in his monograph quotes and confirms this, but in the longitudinal sections 
which he figures, one of which is from the Cowderoy Collection, the base of 
the cone is too worn to show more than that the basal scales are at least 
very nearly as long as those higher up. The lowest scales in this section 
are not barren, but the upturned portion has the appearance of a long thin 
apophysis^ so that it may be true to say that the basal apophyses are 
largest. 
Anatomical Details, - 
i i The Cone-axis. 
The greater part of the slender axis is occupied by a pith com- 
posed of rather thick-walled cells, more or less circular in cross-section, 
and often separated by conspicuous intercellular spaces. From the longi- 
tudinal section it is seen that the cells are elongated in the vertical direction, 
with horizontal or slightly oblique cross-walls, and, in fact, are closely similar 
to those in the axes of recent species. The weakly developed vascular 
cylinder has an external diameter of about 3 to 5 mm., but the width 
of the xylem ring is very small. The limits of the original bundles are 
usually well marked, even where there is a more or less complete ring 
of wood. The xylem consists of regularly arranged radial strands of 
tracheides separated by uniseriate medullary rays. There are no indica- 
tions of centripetal xylem, At certain points in the ring narrow gaps 
mark the exit of the sporophyll-traces. The tracheides of the secondary 
xylem show abundant pitting on their radial walls. The large circular pits, 
which may extend over the whole length of the tracheide, are rather 
irregularly disposed. They are generally uniseriate and not in contact, but 
biseriate pitting is not rare, and in a few cases the pits are alternate 
and, exceptionally, with flattened margins. According to Thomson (14) 
this type of pitting occurs also in the cone-axes of recent species. He 
remarks : c In the primitive regions of the latter (Abietineae) there is 
O o 
