Affinities of the Palaeozoic Seeds of the Conostoma Group. 43 
elimination of members as we pass from those seeds in which the lobes are 
partially free to those in which they are almost completely fused. In 
Pkysostoma , where the multiple integument is most marked, the number is 
ten ; in Lagenostoma Lomaxii , which has a slightly lobed apex, nine ; and 
in Conostoma oblongum , where the lobes are internally almost obliterated, 
six (Text-fig. 13). 
The primitive condition of each member was, we think, that seen in 
Pkysostoma , where the tissue of each tentacle consists of undifferentiated 
parenchyma. As we pass along the series, we find progressive sclerization 
proceeding inwards from the whole periphery of each member, thus tending 
towards the final obliteration of the parenchyma which formed the ‘ loculi 5 of 
the canopy, the sclerization having its inception historically before the fusion 
of the constituent members. In this way the alternate loculi in Conostoma 
anglo-germanicum have disappeared, though still represented exteriorly by 
the minor ribs. This gradual decrease in the number of bundles may have 
culminated in their total suppression, resulting in a condition similar to that 
in the integument of present-day Phanerogams. 
With the more complete fusion of the component members came 
a gradual loss of vascular tissue. This diminution of the vascular supply of 
the ovule was restrained in those forms where, as in Cycads, the motile 
sperms are still retained, but elsewhere, as in most Gymnosperms and the 
whole of the angiospermic series, where siphonogamy has replaced zoidio- 
gamy, the vascular supply tends to become reduced to a mere basal cup with 
rare indication of its distal extensions. Thus this view, which has already 
been put forward, seems to find in these seeds two more links in the chain 
of evidence. 1 
It seems not improbable that, as already suggested, the prominent 
ribbing in C. anglo-germanicum has a definite mechanical value, for the seed 
is an exceptionally long one as compared with its width, whilst the testa be- 
tween the ribs is even thinner than in the much shorter seed of C. oblongum. 
This suggestion seems to find corroboration in Polylophospermum , where, 
too, there is pronounced ribbing associated with a thin sclerotesta and great 
length. 2 From the in tegumental standpoint we can then regard C. anglo- 
germanicum as a late stage of the series, in which only four members remain 
as such, the peripheral portions of all the members still being retained as 
ribs in relation to their mechanical value ; whilst Gnetopsis , with four ribs 
only, probably forms its culmination. 
In the medullosean series of forms there is a similar relation existing 
between ribs and bundles. The latter are, however, situated within the 
sarcotesta and exteriorly to the ribs. In Trigonocarpus Parkinsonii , Br., 
1 Oliver : On the Ovules of the Older Gymnosperms. Ann. of Bot., vol. xvii, 1903, p. 451. 
2 Oliver : Notes on Trigonocarpus and Polylophospermum. New Phyt., vol. iii, No. 4, 1904, 
p. 96. 
