1032 
de Fr ciine. — On the Structure and 
he has extended to me during the progress of the work. Dr. Scott has also 
kindly examined three of the sections, and I have thus had the advantage 
of his valuable opinion as to the identification of the specimen. 
My thanks are also due to W. H. Sutcliffe, Esq., who kindly lent 
me three of his sections of Sutcliffia insignis for purposes of comparison. 
Though the fragment of stem was, as stated, about io inches long 
(25-5 cm.), the series of transverse sections only cover a distance of about 
7 inches (18 cm.). The maximum transverse dimensions were 9JX 3J cm. ; 
it is, however, most probable that the form has been considerably altered by 
lateral pressure, though it is doubtful whether it ever possessed a circular 
contour. A comparison 
with the stem described 
by Scott 1 shows the size 
to be distinctly less than 
in his fossil, in which the 
dimensions were 12 x 6-5 
cm. The specimen was 
cut into three blocks, and 
the further treatment of 
each of these is shown 
in Text-fig. 1. 
Owing to the com- 
plexity of the vascular 
structures present in the 
stem, it appeared desir- 
able to construct a model 
to better elucidate the 
course of the strands. In 
preparation for this the 
outline of the different 
xylem-strands (including 
both primary and second- 
ary tissues) was traced 
from the sections, and 
Text-fig. i. Block A represents the upper end of the specimen, 
as will appear during the course of the paper. 
the tracings were then enlarged to twice the size by the pentagraph. 
The average distance between each section was determined, and wax 
plates of this thickness were prepared, 2 two sheets being used for each 
section, so that the correct proportions as far as possible were maintained. 
The method employed in building up the model from these wax plates was, 
1 Loc. cit., p. 46. 
2 Bees-wax softened with vaseline until the consistency desirable was attained was used ; the 
dental wax commonly employed for this purpose being inappropriate on account of the thinness of 
the sheets. 
