[705] Binney (68), p. 23, Pls. IV. and V.
[706] Schimper (69), p. 330.
[707] For figures and descriptions of this type of cone vide Williamson (73), (80), (89); Hick (93), (94) and Williamson and Scott (94).
[708] Weiss (84), Pls. XXII.—XXIV.
[709] Williamson and Scott (94), p. 911, Pls. LXXXI. and LXXXII.
[710] Vide Heinricher (82); Bower (94), p. 495; Campbell (95), pp. 396, 503.
[711] Williamson (81), Pl. LIV.
[712] An excellent figure illustrating the co-existence of heterospory and secondary thickening is given by Williamson and Scott, loc. cit., Pl. LXXXII. fig. 36.
[713] Weiss (76), p. 103.
[714] Williamson (712).