4o8 
VASCULAR CRYPTOGAMS. 
grooves upon their outer bark surfaces. No single example of a specimen of which the internal 
organisation is preserved — and \ye now possess these in great numbers — sustains this latter con- 
clusion. Wherever the true bark is preserved it exhibits an outline indicating a smooth surface, 
longitudinal internodal flutings and transverse nodal constrictions being alike absent. 
In its young state the bark consisted of undifferentiated cellular tissue, and we now have 
evidence that a hypodermal layer of prosenchyma was developed in it which ultimately attained to 
an enormous thickness. 
The woody wedges extended vertically through each internode without interruption, but at the 
node each wedge split into two halves, each half coalescing with the contiguous half of the wedge 
nearest to it to form one of the wedges of the next internode. At each node in young stems 
numerous small cellulo-vascular bundles passed outwards through the vascular zone to supply some 
peripheral organs ; probably vei ticillate leaves and branches. But most of the latter became 
abortive ; the branches of the larger stems being few, and unsymmetrically disposed. Stems and 
branches were thickened simultaneously as in ordinary exogenous trees. Besides these diver- 
ticula, in most of the Calamites, immediately below each node, there passed outwards, through 
the cells of the large primary medullary rays, so conspicuous in all young shoots, and near the 
medullary surface of matured vascular axes, an exceedingly regular verticil of primary canals, with 
circular or oblong sections, from the central fistular cavity through the woody zone to the bark. 
One of these canals occupied the uppermost end of each of the large cellular rays which separated 
the vascular wedges of each internode. In the common fossilised casts these canals are indicated 
by a very regular verticil of small round or oblong impressions, which some writers have erro- 
neously associated with roots, and others with vascular bundles going to leaves or branches. But 
they never contained any vascular tissues whatever. Of the leaves of Calamites we have but 
little knowledge, although some have identified them with those of Asterophyllites and Spheno- 
phylhim. 
Professor Williamson has only obtained one example of a fruit which he can with confidence 
identify with Calamites (On a new form of Calamitean Strobilus, W^illiamson, in Mem. Lit. Phil. Soc. 
Manch. 3rd ser. IV. p. 248). It is a strobilus the structure of the axis of which corresponds most 
closely with that of a young Calamitean shoot. At each node it has a curiously perforated 
transverse disk fringed with numerous peripheral bracts. From the upper surface of each disk 
there projects vertically upwards a ring of slender sporangiophores, around each of which were 
clustered three or four sporangia full of spores. These sporangia are so compactly compressed 
that a transverse section of this fruit presents the appearance of a compact mass of spores, amongst 
which the outlines of the sporangia are traceable with difficulty. Whilst he has failed to find any 
true stem in which the outer surface of the bark was fluted, that of the internodes of this fruit was 
undoubtedly so. The flutings of the fruit-bark do not, like those seen in the carbonaceous film 
covering the common casts, correspond in number and position with those caused by the woody 
wedges, since two vascular bundles are located in each projecting ridge of the axis of the former 
structure, instead of one as in the latter. 
Mr, Carruthers believes the fruits figured by Mr. Binney, Professor Schimper, and himself, 
under the several names of Calamodendron commune, Calamostachys Binneyana, and Volhmannia 
Binneyi (Journ. of Bot. 1867, pp. 349-356), to belong to Calamites; and he further regards the 
spores as having been furnished with elaters similar to those of Equisetum. Professor Williamson is 
ixnable to agree with either of these conclusions. The numerous specimens which his cabinet now 
contains make it absolutely certain that the supposed elaters are merely fragments of the torn 
mother-cells of the spores, and it is his impression that these fruits, now known to be heterosporous, 
have closer affinities with the Lycopodiaceae than with the EquisetaceDC ; they certainly are not the 
strobili of Calamites^ 
