1906-7.] New Species of Lepidodendron from Petty cur. 207 
XXII. — Note on a New Species of Lepidodendron from Petty cur 
(Lepidodendron Pettycurense). By R. Kidston, F.R.S. L. & E., 
F.G.S., Foreign Mem. Kaiserl. Mineral. Gesell. zu St Petersburg. 
(MS. received July 2, 1907. Read July 15, 1907.) 
Among the undescribed species of plants occurring in the well-known 
material of Calciferous sandstone age found near Pettycur, Fife, is an 
interesting specimen belonging to the older type of Lepidodendroid structure 
which has a solid primary xylem. 
Only two examples of this species are known to me; the larger, of 
which a portion is shown in the text figure, has a central stele 1*10 cm. by 
R90 cm. in diameter, and of this the solid primary xylem is 025 cm. by 
015 cm. in size. 
The slightly elliptical form of the axis is due to lateral pressure, as 
seen by the bands of flattened tracheids which occur in the primary 
xylem. 
The axis of the smaller example is about 2 - 50 mm. by 2 mm. in diameter, 
of which the primary xylem is 1 mm. by G'50 mm., but this specimen has 
also suffered from pressure. 
Returning to the specimen shown in the figure, as seen in transverse 
section, the primary xylem consists of a solid mass of tracheids, irregularly 
placed and varying in size, but the smaller tracheids are mixed with the 
larger without any order (a). 
When close to the periphery of the primary xylem the tracheids become 
smaller and are surrounded by the protoxylem elements (a'), which form a 
narrow band, limiting the centripetal xylem, whose margin is smooth 
without the slightest trace of a corona. 
The secondary or centrifugal xylem is formed of regular rows of 
tracheids which radiate outwards (6). Those next the protoxylem are of 
smaller size, but they increase regularly in diameter as they are traced 
outwards, until they equal or even exceed in size the largest tracheids of 
the primary xylem. 
In longitudinal section the protoxylem elements and primary tracheids 
are very regular in their course, and bear scalariform thickenings. The 
tracheids of the secondary xylem which abut on the primary xylem are 
