A Affinities of 'the Palaeozoic Seeds of the Conostoma Group . 1 5 
the soft-celled tissue of the apex, formed a kind of sarcotesta around the 
seed. The ‘ blow-off’ layer consisted of longitudinally elongated cells with 
an almost uniform radial dimension of about 20 /x. Near the apex, however, 
they reached a maximum of about 80 /x. These cells, as preserved, stand 
in marked contrast with the palisade cells upon which they rest. Their 
interior is almost colourless and their walls are dark and slightly thicker 
towards the exterior. Just below the apex of the seed the cells of this 
layer reached a maximum radial extension (Watson’s specimen 268, PL II, 
Fig. 12, bt.), bevelling off suddenly towards the micropyle, so that the 
extreme end of the seed was covered by an undifferentiated epidermis. 
The chief point of interest is the exfoliation which the ‘blow-off’ 
exhibits : in only one other section besides W. 268 has it remained in situ 
(R. 122, PI. I, Fig. 3, £/.). Elsewhere, the layer stands away from the hard 
testa as if forced off, and in most cases only the basal portions of the radial 
walls remain to indicate its former presence. These latter appear as pro- 
jecting pegs from the margin of the testa, to which they give a crenated 
appearance (R. no, PI. I, Fig. 4, bl.w.) 
The method by which this exfoliation took place is shown in R. in 
(PI. II, Fig. 13, pel) near the apex, where the cuticle-like layer, formed by the 
outer walls, is raised up by cones of mucilage which bear a remarkable 
resemblance to those already described for Lagenostoma Lomaxii '. l But 
whereas the cell- walls in Lagenostoma were raised up as separate entities, in 
Conostoma they formed a continuous layer, which was removed as a whole, 
although it underwent fission, due to its rigidity and lack of elasticity, 
points well shown in one section (R. 116, PL I, Fig. 6, bl.) where the ex- 
foliated f blow-off’ at the apex still retains the lobing of the tissue beneath, 
but, owing to the increased circumference, has fissured along the grooves. 
A section which is perhaps correctly allocated to this seed, viz. R. 113 
(Pl. I, Fig. 9), is presumably an oblique transverse section passing through 
the stalk. It was winged with a central cavity ( c.s .), probably lysigenetic, 
and a narrow, angled band of hard tissue following the outline of the 
exterior (set,). Its attribution rests upon the general appearance of its 
tissues, bounded at the exterior by an epidermis which closely resembles the 
‘ blow-off’ layer as seen in certain of the sections. Its prominent wings, 
to the number of seven, corresponding to seven vascular bundles ( v.b .), 
might well have been the base of such a seed as R. no, which, as we have 
already pointed out, varied in this respect from the normal number of ribs, 
the hard tissue being perhaps the basal limit of the testa. The chief diffi- 
culties in the way of its acceptance are (a) the rapidity with which the 
bundles are passing out, and (b) the presence in the wings of secretory 
passages (j./.),one in each. In any case it seems possible that the bundles 
of Conostoma remained distinct for some distance below the seed-base, 
1 Oliver and Scott : On Lagenostoma Lomaxii. Phil. Trans., B, vol. 197, p. 206. 
