7 6 
Oliver. — On Physostoma elegans, Williamson , 
A-D cut at different levels (Text-fig. 2) The photograph of an almost 
median longitudinal section of the upper portion of a seed (PL V, Fig. 4) 
shows two of the tentacles 
cut in the direction of their 
length (t 0 and / 6 ), the inser- 
tion of the left-hand tentacle 
being particularly clear. Four 
other tentacles, cut transverse- 
ly or obliquely, are shown at 
t 19 t 2i t 3 , and / 4 , immediately 
above the pollen-chamber (/). 
Nor should reference be omit- 
ted to Williamson’s original 
figure. Published thirty years 
ago, and based on a rather 
thick section, this drawing 
shows the relations of the 
upper part of the nucellus 
and tentacles with unerring 
accuracy, and could hardly 
J3 be improved upon. 1 
A very striking feature 
about Physostoma , and one 
which makes even the smallest 
fragments easy of identifica- 
tion among the heterogeneous 
assortment of petrified plant- 
remains that go to form a 
coal-ball, is the conspicuous 
investment of long, club- 
shaped hairs which clothe the 
summits of the ridges on the 
body of the seed, and the 
outer (abaxial) faces of the 
tentacles. These hairs are 
commonly to be found with 
excellent preservation, and 
reach a length of *5 mm. or 
more in the neighbourhood 
of the median line of ridge 
and tentacle respectively. No doubt, during life, they almost completely 
enveloped the seed (see the oblique section of an apex, PI. V, Fig. 8). 
1 Williamson, eighth Memoir, Phil. Trans., 1877, PI. XI, Fig. 77. 
Text-fig. i. Diagrammatic median longitudinal sec- 
tion of Physostoma elegans. The integument is obliquely 
shaded : the secretory zone is omitted for the sake of 
clearness, whilst the tapetum is represented as a single 
layer in black; the vascular strands are left unshaded. 
The letters A, B, C, and D refer to the heights at which the 
transverse sections in Text-fig. 2 are cut. 
