77 
ture was intermediate between that of Calamodendron and 
Calamopitus. In the general arrangement of their separate 
parts these new specimens corresponded most closely with 
the well known type figured by Mr. Binney ; but they differ 
in two important particulars. All their fibrovascular tis- 
sues are of the reticulate type seen in Calamopitus and 
Dictyoxylon. with here and there a few scalariform vessels 
interspersed. The cellular laminae separating the vascular 
wedges again exhibit remarkable variations even in the same 
specimen; their cells being sometimes elongated into vertical 
forms of prosenchyma — at others they are extended trans- 
versely, parallel to a tangential section — whilst still more fre- 
quently they consist of ordinary parenchyma. In another 
feature also the specimens exhibit considerable variations 
In some the fibro-vascular tissues of the vascular wedges are 
separated by masses of cellular tissue, not only at the nodes 
but also at the internodes. These tissues which, viewed physio- 
logically, can only be regarded as modified medullary rays, 
are so numerous in one example that more than two vertical 
vessels can rarely be found in contact without the interven- 
tion of one of these vertical rows of mural cellular tissue. In 
some other examples these medullary rays are much more 
scanty, as if connecting the type under consideration with 
that figured by Mr. Binney. The verticillate medullary 
radii of Calamopitus are wholly wanting in these new ex- 
amples. Additional proof is thus afforded that all the three 
types referred to may be but variations, possibly having no 
more than specific value, and perhaps not always even that, 
of the common type of Calamodendron : and it thus becomes 
increasingly demonstrable that in the Lancashire coalfield, 
whatever may be the case elsewhere, we have no evidence 
of the existence of an Equisetiform type of Calamite distinct 
from the Calamodendroid one. 
Professor Williamson further announced the discovery by 
Mr. Butterworth of a young Calamite in which the cortical 
