98 
PROFESSOR W. C. WILLIAMSON ON THE ORGANISATION 
base, cuneiformes, entik*es, ou dmargindes, ou mdme bifides, a lobes plus ou moins pro- 
fondement lacinies.” 
His genus, AsteropliylUtes, he defined as having “ feuilles planes, plus ou moins 
lineaires, aigues, traversees par une nervure moyenne simple, fibres jusqu’a la base.”^’" 
In his ‘ Tableau des Genres de Yegetaux Fossiles,’ published in 1849, he again 
defines the two above genera in almost identical words, adding, however, that Spheno- 
phyllivm differs from Asterophyllites, “ par le nombre beaucoup moindre ce ces organes 
a chaque verticille, 6 a 8 ou 10, et par leur forme qui est triangulaire, tronquee au 
sommet, ou dentee et lobee, quelquefois tr^s profonddment ” {loc. cit., p. 52). 
In 1864 Messrs. Coemans and Kikx published their “ Monographic des Spheno- 
phyllum d’Europe.” In it they define the leaves as “ cuneatis, sessilibus, verticillatis, 
nervo medio destitutis; nervulis autem sequalibus, dichotomis” {loc. cit., p. 414). 
In my Memoir, Part V.,t I described a plant in which each foliar verticil consisted 
of 18 linear uninerved leaves, which characters identified it unquestionably with 
Asterophyllites. That these leaves have the characteristics of Asterophyllites and not 
of Splienopliyllum, is demonstrated by the numerous long and transverse sections of 
them in figs. 5, 14, 15, 16, and 17 of the above memoir, in which also the remarkable 
structure and development of the stem of the plant is described. 
In May, 1870, M. Renault had presented to the French Academy a memoir, 
“Recherches sur fiOrganisation des Splienopliyllum et des Annularial' but owing to 
the siege of Paris, during which the drawings were lost, the plates were only published 
in the ‘ Annales des Sciences Naturelles, Botanique,’ 5® serie, tome 18, 1873.J 
In this memoir, M. Renault described the internal structure of Splienopliyllum 
Stephanense, which structure proved to be identical, in most respects, with that of my 
Asterophyllitean stem. On the strength of this resemblance, M. Renault and 
H. Grae zu Solms-Laubach, have contended that I ought to have designated my 
plant a Splienopliyllum, and not an Asterophyllites. I, on the other hand, still insist 
that, in accordance with the definition of every author who has written on the 
subject, my uninerved leaves prove my plant not to be a Splienopliyllum, but rather 
demonstrate the very intimate relationship, not to say identity, of the two genera, at 
least, so far as some forms of Asterophyllites are concerned. Some others are 
unc[uestionably the leaves of Calamites. 
The position of the Volhmannia Dawsoni referred to above, is affected by this 
controversy. In M. Renault’s memoir, p. 9, there appears a note by M. Brongniart, 
aprop)os of my memoir of 1871 in the Manchester Transactions. M. Brongniart says, 
“ Ce travail s’accorde dans plusieurs points importants avec les rfisultats obtenus un 
* ‘ Prodrome,’ pp. 68 and 159. 
t ‘ Pliil. Trans.,’ 1874, p. 41, et seq., but delivered to the Royal Society on May 17, 1873. 
I By a coincidence M. Renault’s memoir, as now constituted, was only delivered to the Academy on 
May 13, 1873, four days before mine was delivered to the Royal Society. 
