PROFESSOR W. WILLIAMSON ON THE ORGANIZATION 
spokes of fig. 31. Whatever these latter objects may have been, they are very 
remarkable and uncommon appendages to a vegetable stem. They coexisted with a 
thick vascular Calamodendroid zone, and it is their medullary extremities that are repre- 
sented by the scars, l, of fig. 30 ; even when that vascular zone has disappeared, and 
nothing remains but the inorganic cast of the medullary cavity, these scars also remain, 
indicating the former existence of the canals to which they owe them origin. Both 
these verticils of nodal appendages are discoverable in most of the objects recognised as 
Calamites by Brongniart, Grand-’Eury, and those who agree with the French school 
of palseo-phytologists on this point. Yet I am asked to believe that these extraordinary 
combinations of detailed structural resemblances are to be found in two classes of 
plants so remote from each other as are the Cryptogamic Equisetacese and the Gymnos- 
perrns. Surely such an instance of mimicry as this would, if true, be far more 
remarkable than any of Mr. Wallace’s illustrations of that curious phenomenon. 
But I am convinced that it is not true, and still hold that all the suppositious 
distinctions upon which M. Grand-’Eury relies in his recent volume, for separating 
Calamites from Calamodendra are fallacious ones, and that they are altogether out- 
weighed by the structural identities to which I now once more call attention. 
Asterophyllites. 
The next specimen to be noticed is one throwing additional light upon some 
described in my fifth memoir as belonging to the genus Asterophyllites. It will be 
remembered that M. Renault described certain stems which he regarded as those 
of Sphenophyllum, and he was doubtless justified in doing so. In the memoir 
referred to I showed that numerous stems which I believed to be those of Astero- 
pyllites had, typically, the same structure as those of Sphenophyllum. In his recent 
work on the coal-measures and coal-plants of central France, my friend M. Grand 
’Eury disputes the correctness of my determination. He says, “ II est done, en 
tout cas, bien certain que nous avons a faire a la structure des tiges de Sphenophyllum, 
et non a celle des Asterophyllites, comme M. Williamson le pretend, d’apres des 
exemplaires calcifies munis de feuilles plus nombreuses, apparemment simples ; mais 
le Bechera grandis parait se rapporter a quelque Sphenophyllum, et je connais des 
tiges de Sphenophyllum angustifolium avec de nombreuses feuilles aciculaires a 
peine soudees legerement deux a deux a la base.”* In my memoir, Part V., 
pp. 48, 49, I calculated that the plants there described must have had about 24 
long linear leaves in each verticil, and I further pointed out that the transverse 
sections of these leaves ( loc . cit., Plate IIP, figs. 14, 17) displayed a central 
thickening, indicative of the existence of a single midrib to each leaf. The specimen 
which I now figure, fig. 32, is a transverse section of the same stem as that repre- 
sented in fig. 2 of Part Y. of my memoirs, but that figure merely represented a 
section of an internode. The section now published has passed obliquely through a 
* ‘ Flore Carbonifere Botanique,’ p. 50. 
