42 Penhallow . — N ematophy ton Ortoni, n. sp. 
The hand-specimen transmitted to us for examination is 
15 cm. high and 14 cm. broad at the base, from which it 
gradually tapers upward in such a way as to suggest that 
it must be the base of a stem. This idea is strengthened by 
the presence of a number of basal and lateral processes with 
their outward terminations presenting fractured surfaces, show- 
ing that they represent the bases of more or less prolonged 
organs such as roots. Between these processes are rounded 
indentations, such as may be supposed to have been made by 
large pebbles. In fact, to those who are familiar with the 
branching base of a Laminarian stipe, the resemblance between 
the two is very striking. But Prof. Orton informs me that 
this specimen was originally part of a very much larger one 
which was broken in getting it out of the shale. The largest 
fragment thus obtained measured about 20 inches long and 
8 to 10 inches wide. A photograph of it shows the surface 
to be irregularly indented with several processes, the whole 
presenting the general aspect of the smaller specimen taken 
from it. It is clear then that the original plant must have 
been one of rather large dimensions, on the scale of a tree, 
and the general external characters of the specimens justify 
the view that they represent the base of a stem or stipe at the 
point whence the roots issue. 
Internally the specimen is highly silicified throughout, 
and shows no evidence whatever of concentric structure. 
Externally there are limited areas covered with a friable, 
carbonaceous film which, in places, attains a thickness of 
about 1 *5 mm., but for the most part it is very thin. It in 
all probability represents the carbonised residue of the cortical 
tissue, although microscopical examination fails to disclose 
any definite structure. We can therefore only assume that it 
represents cortex, a view, however, which finds its justification 
in our general knowledge of the alterations in such structures 
under similar conditions. 
The first sections examined were received from Prof. Orton, 
but they got badly broken in transit, in consequence of which, 
and also for the purpose of ascertaining the relation of struc- 
