an archaic type of Seed from the Palaeozoic Rocks . 107 
zone of tissue interposed between the sporangial wall and the spore-com- 
plex. Of these perhaps Grand’ Eury’s Schizostachys grandosus is the most 
notable example . 1 
(c) The Form of the Megaspore-cavity and Pollen-chamber. The 
conical prolongation of the megaspore-chamber at the apex is another 
curious feature which must not be passed over. It vividly recalls in some- 
what generalized form the beak-like process of the embryo-sac in Ginkgo , 
Cardiocarpus sclerotesla. 
Pliysostoma 
el eg a ns. 
Text-fig. 9. Diagrammatic longitudinal sections of the apices of the ovules of Ginkgo , Cardio- 
carpns , and Physostoma, showing the ‘ tent-pole ’-like papilla of the megaspore. The gametophyte 
is represented by vertical lines, the nucellus is dotted, and the integument given in broken outline, 
pollen-chamber. 
which Hirase compared with a tent-pole, holding up the roof of the pollen- 
chamber . 2 As Scott was the first to point out, a similar structure is found 
in several Cordaitean seeds . 3 The interest attaching to this correspondence 
1 Flore Carbonifere, p. 201, and tab. xvii. d and d l , Other cases are enumerated in my 
‘ Vascular Sporangium New Phytologist. vol. i, pp. 62-3. 
2 S. Hirase, Etudes sur la Fecondation, etc. du Ginkgo biloba , Journ. of the Coll. Science, 
Japan, vol. xii, p. 113, and PI. IX, Figs. 35 and 36. 
3 Studies in Fossil Botany, 1900, p. 440. Numerous ‘tent-poles’ are figured in Brongniart’s 
1 Les graines silicifi^es PI. II, Fig. 2 ; PI. V, Fig. 5 ; PI. VI, Fig. 7 ; Pl. XI, Fig. 4 ; PI. XII, 
Figs. 1 and 2 ; PI. XV, Fig. 5. See also Coulter and Chamberlain, ‘ Morphology of Spermo* 
phytes,’ pt. i, Gymnosperms, p. 140. 
