Affinities of the Palaeozoic Seeds of the Conostoma Group . 9 
The canopy shows conspicuous lobing, each of the six lobes corresponding 
to a ridge. The six vascular strands which enter the seed at the chalaza 
traverse the soft lining of the hard shell of the testa below the ridges and 
angles, and, continuing to the apex, enter the lobes of the canopy. The 
surface layer of the seed appears to have undergone mucilaginous degenera- 
tion, thus recalling the condition of Lagenostoma . Curiously enough, the 
actual tip of the seed was succulent, thus contrasting in a striking way with 
the otherwise sclerotic texture of the integument. This unique feature may 
well have been correlated with secretory activity at the moment of pollen 
reception. 
The nucellus, which, as usual, stood erect in the axis of the seed, had 
a length of 3-7 mm. over all. Its lower 3-1 mm., coalescent throughout 
with the testa, were occupied by the megaspore cavity, which possessed 
a well-marked tapetal lining or jacket. The free summit of the nucellus, 
which was closely ensheathed by the lining layer of the integument, was 
dome-shaped, the dome resting on the tapetal septum which stretched 
across the nucellus at this level. Above, in the centre of the convex 
extremity, was a low depression or dimple on which rested the smallest 
pollen-chamber we have seen in an English seed. This pollen-chamber 
— or lagenostome, as we prefer to call it — was a tiny, truncated, globular 
body, open above, and possessed a one-layered wall of characteristically 
sculptured cells. Its mouth lay immediately below the micropylar tube of 
the integument, which was clamped to the rim of the lagenostome by a 
ring-like flange (Text-fig. 5, ///., p. 17). In this way the efficient transport 
of pollen would be amply secured. Pollen-grains when present in the seed 
have never been found in the lagenostome, which would appear to have 
served in this case merely as a vestibule to a more spacious lower chamber 
occupying the interior of the plinth. Into this lower chamber the unusually 
large pollen-grains were conveyed through the collapse of the floor of the 
lagenostome. The details of this curious mechanism, so far as we appre- 
hend them, will be fully set forth in the sequel. 
The main points in the structure of this interesting seed which merit 
full description are (1) the testa with its wings, succulent tip, and highly 
specialized micropyle ; (2) the free part of the nucellus closely invested by 
the lining of the integument and consisting of a two-storied appliance for 
the reception and maturation of the pollen. 
We embody in the accompanying Text-fig. 3 an attempt to reconstruct 
the median longitudinal section of this seed, together with transverse 
reconstructions at the several heights indicated. 
3. The Testa. 
The hard part of the testa which gave form to the seed was of 
a rounded, hexagonal shape, tapering with a steep curve towards the micro- 
