HICK : SOME RECENT ADVANCES IN BRITISH PAL^EOBOTANY. 55 
conclusion, that, all things considered, the anatomical structure of 
Lepidodendron approximates most closely to that of the Psilotacece. 
The structure of the Sporangia of Lepidodendron is described 
with some detail in his elaborate memoir on The Morphology of the 
Spore-producing Members of the Equisetinew and Lycopodinece* 
Here it is shown that the sporangia of Lepidodendron are of two 
types. In Lepidostrohus Brownii, Schimp., "the sporangial wall is 
several layers of cells in thickness, and the cavity traversed by rod- 
like masses of tissue (trabeculse), while, in other forms, the wall 
consists of a single layer when mature, and the cavity traversed by 
one or more irregular plates of sterile tissue." In both cases, how- 
ever, the sterile tissues spring from the floor of the sporangium, 
which projects into the cavity to form the sub-archesporial pad," 
and, though it is not proved, it seems probable that they are similar 
in their origin to the trabeculae of Isoetes. 
Myeloxylon, Brongt. 
In a paper on this genus of Carboniferous plants,t whose affini- 
ties have hitherto been more or less undecided, Mr. A. C. Seward 
brings forward a number of fresh observations in support of the view 
that it agrees more closely with recent Cycads than with Ferns. 
They are based upon specimens of Myeloxylon from the Millstone 
Grit, sections of petioles in the Binney Collection, in the Wood- 
wardian Museum, Cambridge, and a preparation in the Williamson 
Collection. It is not pretended that the evidence these specimens 
afford is sufficient for a final decision on the affinities of Myeloxylony 
but it seems to bear out, to a large extent, the author's conclusion 
that " Myeloxylon should be looked upon as an extinct genus, not 
exactly corresponding to any recent family of plants, but one which 
comes very near to the Cycadese in anatomatical structure, and prob- 
ably occupies a position between Cycads and Ferns, but nearer to the 
former than to the latter." 
In another paperj the same author describes a new Fern from 
the Coal Measures, under the name of Rachiopteris Williamsoni. 
* Phil. Trans., vol. clxxxv. (1894) B. 
t Annals of Botany, vol. viL, pp. 1-20. 
J Annals of Botany, vol. viii., pp. 207-218. 
