148 BOTANICAL GAZETTE [FEBRUARY 
nettitales, it is worth while to consider how a compact cone has 
probably been derived from a loose crown of sporophylls, and how 
the terminal position of cones may have succeeded the lateral. The 
compact cone, found everywhere in living cycads, except in the 
ovulate plant of Cycas, has in all probability been derived from a 
loose crown of sporophylls like those of the Cycadofilicales and the 
staminate sporophylls of Bennettitales, and like the ovulate 
sporophylls of Cycas. Various species of Cycas show stages in the 
advance from this loose crown of leaflike sporophylls toward the 
compact cone composed of sporophylls so highly modified that 
their leafy nature is very much obscured. In Cycas revoluta the 
sporophylls are quite leaflike and bear five or more ovules; in C. 
circinalis the pinnae are much more reduced, appearing only as 
serrations on the edge of the much reduced blade; in C. media the 
sporophyll is equally reduced and frequently bears only two ovules; 
in C. Normanbyana the sporophy]ll is about as in C. media, but there 
are regularly only two ovules. From the sporophyll of C. Nor- 
manbyana to that of Dioon edule the transition is easy, and the loose 
cone of D. edule does not differ much in appearance from early 
stages in the development of the ovulate structures of Cycas. The 
distinguishing feature is that in the ovulate plant of Cycas the 
meristem never becomes converted into sporophylls, but continues 
the growth of the axis. From the condition in Dioon to the more 
compact cones of the remaining genera, the transition is easier still, 
and consists principally in shortening the blade of the leaf until it 
finally reaches the almost peltate sporophyll of Microcycas and 
Zamia. Occasionally a proliferating cone reminds one of the 
Cycas condition. 
In the reduction of the number of cones, and in the evolution of 
the compact cone from a loose crown of sporophylls, we have two 
independent series of changes, which may or may not have pro- 
gressed with equal rapidity. Loose staminate sporophylls and 
numerous lateral cones are characteristic of the Bennettitales. 
The combination of loose sporophylls and numerous lateral cones 
is not found in any living cycad, but loose sporophylls are found - 
the ovulate plant of Cycas, and numerous lateral cones are found in 
Macrozamia Moorei, the staminate cones being almost as numerous 
