THE LIVING CYCADS AND THE PHYLOGENY OF SEED PLANTS 1 53 
and we have tried to emphasize the second claim by showing that the 
Coniferophytes and Angiosperms — the undoubted progeny of something — 
can be referred to another ancestry. 
EXPLANATION OF PLATE VI 
Diagram illustrating some features of the Cycadophytes and Coniferophytes. 
At the bottom: L, a diagrammatic representation of a member of the Cycadofilicales, 
with a transverse section of the stem at the right; an idealistic view of spore-producing 
members; P, pinnule of Pecopteris with seeds on the margin. 
In the middle: A, habit of one of the Bennettitales with section of stem; B, bispor- 
angiate strobilus; S, two seeds on long stalks and two scales. 
At the top : habit of a living cycad ; C, sporophyll of Cycas with crown of sporophylls 
at the right; D, Dioon; M, Macrozamia; E, Encephalartos; each with corresponding cones 
at right; H, male cone with a single sporophyll below. All very diagrammatic. 
