Mesoxylon and an Allied Gams. 19 
being a single species, may possibly represent an assemblage of seeds 
belonging to closely allied plants.’ 
It is therefore not impossible that seeds of the Mitrospermum com - 
pressum type, at present indistinguishable from one another, may have 
been borne both by Mesoxylon multirame and Mesoxylopsis Arherae . But, 
in the existing state of our knowledge, we are not justified in making any 
such assumption, and the significance of the evidence from association 
in the two cases is at present quite doubtful. Considering, however, that 
the fertile shoots of Mesoxylon midtirame have now been shown to agree in 
morphology and structure v/ith a Cordaianthus y it is highly probable that 
the platyspermic seeds associated with them may have really belonged 
to the plant. 
The genus Diplotesta, to which Bertrand referred the ovules of his 
Cordaiantkus (Bertrand, 1911), appears to be closely allied to Mitrospermum 
(Brongniart, 1881, Pis. XIII and XIV ; Bertrand, 1907), and the latter 
genus is in every respect a seed of the type which there is good reason for 
attributing to the Cordaitales (see Seward, 1917, pp. 332 - 56 ). 
The main result of the present investigation is, however, the proof that 
Mesoxylon multirame bore a Cordaianthus in all respects comparable to the 
inflorescence of Cordaites. The close affinity of the two genera and the 
definite location of Mesoxylon in the family Cordaiteae are thus securely 
established. There is little doubt that the new genus Mesoxylopsis is 
of like affinities, but further evidence is needed before its exact position 
can be determined. 
While the evidence from association with seeds has proved too 
uncertain to be relied on, great credit is due to Mr, James Lomax for 
calling attention to the shoots described in the present paper. In the 
case of the fertile branches of Mesoxylon multirame his conviction of their 
‘ fructiferous ’ nature has been fully confirmed. 
The photographic illustrations to the present communication are the 
work of Mr. W. Tams of Cambridge. The drawings, both the text-, 
figures and those in the plate, are from the pencil of Mr. G. T. G william, 
F.R.A.S. To both these gentlemen I desire to return my thanks for their 
skilful aid. 
References. 
Arber, Agnes (1910) : A Note on Cardiocarpon compression, 'WiM. Proc. Cambridge Philosophical 
Soc., vol. xv, pt. v, p. 303. 
(1912) : On the Structure of the Palaeozoic Seed Mitrospermum compression (Will.), 
Ann. Bot., vol. xxiv, p. 491. 
Bertrand, C. E. (1907) : Les caracteristiques du genre Diplotesta de Brongniart. Bull, de la Soc* 
Bot. de France, 4® serie, tome vii, p. 389. 
