an archaic type of Seed from the Palaeozoic Rocks . 
77 
This indeed they still do in the petrifactions in the region of the free 
arms of the integument, but on the body of the seed they tend to 
stick together — thus exposing 
the grooves between the ribs 
— instead of diverging fan-wise, 
as occasional examples indicate 
to have been the position during 
life (PL VI, Fig. 13). That the 
investment by the hairs was 
complete is shown by the very 
tangentially cut section from 
the base of a seed given at 
PL VI, Fig. 22 ( t.k. )h The 
upper third of the drawing 
represents the section where, 
after leaving the tissues of the 
seed proper, it traverses the 
covering of hairs in an oblique, 
upward direction. At the top 
of the figure, where the section 
runs through the outskirts, only 
the longest hairs reach the plane 
of section. 
The vascular system of 
the seed has essentially the 
same distribution as in La- 
genostoma Lomaxii. A supply 
bundle enters at the rather 
exiguous seed base, and at once 
separates into as many strands 
as there are ribs. The strands 
run up the seed deep down in 
the substance of the ribs — at 
about the level of the interven- 
ing grooves — and pass out into 
the tentacles. No vascular con- 
nexions have been traced to the 
pollen-chamber. 
The general ground-sub- 
stance of the testa is a rather 
thin - walled, closely - fitting 
tissue of prismatic cells, elongated in a 
D 
c 
B 
A 
Text- fig. 2. Series of diagrammatic transverse 
sections of Physostoma elegans. The letters A, B, C, 
and D correspond with the heights, in Text-fig. 1, to 
which the sections belong. Shading, &c., as in Fig. 1. 
direction parallel to the axis of 
The plane of section is plotted is Text-fig. 3, p. 80, R. 72, a. 
