A Vascular Sporangium. 63 
given above for Zygopteris. In his later writings Renault 1 
recognises B. dnbius as a Zygopteris, though in a note in his 
Zygopteris paper 3 he had expressed a doubt as to the possibility of 
such a reference. I am unaware whether the evidence upon which 
this change of opinion is based has been published. Whilst 
agreeing with Zygopteris in the position, form and dimensions of 
the sporangia, B. dubius seems to have but a unilateral annulus, 
whilst in the complexity of its wall it much surpasses that which 
has been described for Zygopteris. 
Botryopteris forensis, B. R.—The sporangia are smaller than in 
either of the foregoing, the length of the sporangium being 1.5—- 
2 mm., its diameter .7—1.0 mm., whilst its spores attain a diameter 
of .06—.07 mm. The wall is described as being two-layered, 3 i. e , 
an outside limiting layer one cell thick, enlarged on one side to form 
the annulus, and a thin-walled, often indistinct, lining. 
Of the forms just detailed our sporangium approaches most 
nearly in dimensions to B. forensis, but its spores have a diameter 
of only one-third (.02 mm. as compared with .06—.07 mm.), a 
disparity perhaps explicable in view of the immature condition of 
the sporangium and the collapsed condition of the spores. With 
B. dubius it has a point of contact in the lining of elongated cells 
which that sporangium possesses. Finally, the little vascular 
bundles which Renault has traced into the pedicels of Zygopteris 
render the assumption that this sporangium may have possessed a 
vascular coat not a very hazardous one. Indeed if B. dubius be 
really a Zygopteris with a well preserved wall, the elongated cells of 
the lining may have been tracheal in nature, a remark likewise 
applicable to the inner layer of Schizostacliys. Hence it would 
appear as not wholly improbable that a tracheal layer in the 
sporangial wall of Botriopteridese may have been a common 
character. As yet the evidence is lacking, and in any case can only 
be expected to accrue slowly from occasional and exceptionally 
preserved specimens. 
But there is another group, the Marattiaceae, that should not 
be omitted from consideration as affording a possible resting place 
for our sporangium. Of the numerous Pecopteroid and other 
fructifications that have been attributed to this order, several show 
the rudiments of an annulus. Such a form with unmistakeable 
'Flore fossile d’Autun et d’Epinnc, pt. ii., p. 42. 
2 Ann. des Sci. Nat. (Bot.), ser. vi., vol. iii., p. 23. 
3 Flore fossile d’Autun et d’Epiuac, pt. ii., p. 54. 
