Affinities of the Palaeozoic Seeds of the Conostoma Group . 49 
Fig. 2. Apex of young seed cut obliquely, showing the plinth jacket (pi. j.) and wall of plinth 
(pi.) in close contact. The cells of the testa (t.) show contents, and the plinth tissue is slightly 
displaced from the base of the lagenostome (Ig.). U. C. L., R. 114 (Halifax). x 80 (see 
pp. 12, 14). 
Fig. 3. Apex of young seed cut tangentially. The 4 blow-off’ layer (bl.) is in position on the 
left, but on the right has exfoliated. The cells of the soft apical tissue (si.) are well shown and pass 
gradually into the hard tissue below (i.). U. C. L., R. 122 (Shore), x 70 (see pp. 12 and 15). 
Fig. 4. Oblique section through winged base of seed, showing basal portions of the cell-walls ot 
the 4 blow-off’ layer still attached (bl.w.) to the prominent wings of the base (r 4 , r 5 , r 6 ). U. C. L., 
R. no (Dulesgate). x 36 (see p. 15). 
Fig. 5. Transverse section through middle region of seed. The somewhat flattened outline is 
well shown and the structure of the testa with outer palisade (pa.) and inner fibrous layers (fb.). 
ma. and ini., major and minor angles. U. C. L., R. 119 (Shore), x 26 (see p. 10). 
Fig. 6. Oblique section through apex, showing three lobes of 4 blow-off’ (bl.). The cells of the 
cushion (Is.) are well preserved. Ig. lagenostome wall ; m.m., micropylar membrane ; pi., plinth. 
U. C. L., R. 1 16 (Shore), x 70 (see p. 18). 
Fig. 7. Median longitudinal section through apex of same specimen as Fig. 1, showing the 
micropylar membrane (m.m.) cut obliquely and consisting above of superimposed tiers of cells. 
The lagenostome (Ig.) is cut tangentially, bl., ‘blow-off’ layer; Is., lens or residue of plinth 
tissue. U. C. L., R. m (Shore), x 100 (see p. 14). 
Fig. 8. Oblique section through micropyle, showing the soft tissue at the apex (s.i.) separating 
from the testa below (i.); the loculus of the canopy on the right (loc.) shows the vascular bundle 
(v.b.). m.m., micropylar membrane. W. 267 (Shore), x 64 (see p. 12). 
Fig. 9. Transverse section of base of seed, showing seven wings, bl., ‘blow-off’; scl., scleren- 
chymatous cells ; v.b., vascular bundles ; c.s., central space ; sp., one of the secretory passages. 
U. C. L., R. 1 13 (Halifax), x 40 (see p. 15). 
Fig. 10. Somewhat oblique longitudinal section through seed passing out above the stalk ; 
seven ribs are present (r l , r 2 , . . .), two of them with their vascular bundles preserved (v.b. 5 , 
v.b?). s., sinus; Ig., lagenostome; Is., lens; pd., pad. U. C. L., R. no (Dulesgate). x 18 
(see p. 12). 
Fig. 11. Doubly oblique section through seed, showing contained prothallus (pr.) with ‘tent- 
pole ’ (t.p.) ; the shoulders of the plinth cavity (pl.c.) are exaggerated by the direction of the section. 
bl., 4 blow-off’; r’ and r 2 , ribs asymmetrically cut. U. C. L., R. 119 (Shore), x 30 (see p. 12). 
PLATE II. 
Figs. 12-20 (Photographs). 
Fig. 12. Oblique section of seed above the lagenostome, showing the soft apical tissue above 
(s.i.) and with ‘blow-off’ (bl.) exterior to it. The micropyle is in the centre of the figure, its lining 
membrane (m.m.) is seen as a fluted layer. At the top of the figure are two somewhat displaced 
lobes of the canopy (/., /.) with a sinus (i 1 .) between. W. 268 (Shore), x 70 (see p. 13). 
Fig. 13. Portion of apex of seed given in PI. I, Fig. 1, showing the outer edge of the testa 
‘blow-off’ raised up by pegs of mucilage beneath (pel) ; m.m., micropylar membrane. U. C. L., 
R. hi (Shore), x 195 (seep. 15). 
Fig. 14. Median longitudinal section through lagenostome, plinth, and adjacent parts. 
Ig., lagenostome with apparently two wall layers; pi., wall of plinth; tl.j., plinth jacket; s., 
foot of sinus between plinth and plinth jacket ; Is., remains of plinth tissue (‘ lens ’) adhering to 
lagenostome; pd., pad resting on tapetum ; v.b., position of vascular strand. U. C. L., R. no 
(Dulesgate). x 85 (see p. 20). 
Fig. 15. Central part of Fig. 16 enlarged, pd., central pad resting on remains of plinth tissue 
(pl.t.) ; p.g., pollen-grains, the upper right-hand one with internal cells. U. C. L., R. 117 (Shore) 
x 182 (see p. 20). 
Fig. 16. Longitudinal section of upper part of seed, showing testa (/.), and base of micropyle 
(me.), lagenostome (Ig.), plinth (pi.), and remains of tissue of plinth (pl.t.) resting on the tapetal 
septum (tap.) ; part of the tapetum has separated as a blister. Around the pad are several pollen- 
grains (p.g.). loc., loculus of canopy; s., base of sinus between plinth and plinth jacket. Photo- 
graphed by Mr. W. Tams. U. C. L., R. t 1 7 (Shore), x 38 (see p. 20). 
E 
