22 4 
Notes . 
their structure agreed in general plan with that of C odium, as 
shown in Kiitzing, ‘ Phycologia Generalis/ PI. 42, Fig. 1. 
“ As a possible algal nature has been suggested for P achy theca 
by Mr. Etheridge, I think it may not be considered presumptuous 
on my part to now state that I have been of opinion ever since 
I studied the sections, that Prototaxites and Pachytheca are both 
referable to the same morphological type of structure. The 
radiating cells in the latter terminate internally in loosely inter- 
lacing slender filaments, with which the central cavity has been 
apparently filled. Pachytheca does not resemble any type of 
sporangium with which I am acquainted ; the structure, as dis- 
played in the specimens, has a certain resemblance to that of the 
sporocarp of Pilularia ; but I cannot reconcile what I have seen 
of it with the supposition that it was a reproductive structure 
belonging to any type of vascular cryptogam. 
‘ According to the view which I take of Pachytheca , it was an 
algal organism closely resembling in essential structure a diminu- 
tive Codium , but with the peripheral cells branched instead of 
simple. I do not see any evidence to lead me to suppose that it 
was related to Prototaxites as a sporangial organ. The existence 
of Prototaxites on modern biological views necessarily implies 
the existence, at some time or other, of allied forms, and I do not 
see why Pachytheca should not have been a contemporaneous 
one.” * 
I should not recall the past history of an observation, which to me 
is not of very great importance, were it not that in his paper Sir 
Joseph Hooker pointed out that I stood alone in asserting that the 
cells of the cortical and peripheral tissue were continuous. ‘ This 
organic connection/ he says, ‘ between the tissue of the cavity and 
walls is, if confirmed, a fact of very great importance. It has escaped 
my own notice and that of several excellent observers, who had 
devoted much time to the study of my specimens. 1 ' I think it is not 
without interest to point out that it has been confirmed. Mr. Barber 
has obtained independent evidence of the fact in one of the 
sections, which I myself have not seen, described in his present paper. 
He remarks, however, 1 this is, I believe, the first specimen, if not the 
only one, in which cortical and medullary filaments have been seen to 
join one another/ I can only say that I determined the fact of their 
1 Annals of Botany, III, pp. 138, 139. 
