compared with other genera of Cycadeae . 6 1 1 
elements, of which the innermost one or two are seen to 
be lignified and represent fibres. This probably represents 
the same formation as the inverted small bundle above 
described, although, in this case, no xylem has been added 
by the cambium. 
If we now pass outward beyond the first anomalous ring, 
on its immediate outer limit a third zone is met with, 
composed of bundles or segments, as above stated, which 
are very much smaller in size and less closely and compactly 
arranged than those of the first two rings. This zone con- 
stitutes the second definite anomalous ring produced by an 
extra-fascicular cambium. The segments composing it have 
the usual wedge-shaped contour, and in many parts of the 
stem are very irregularly arranged. They often leave the 
vertical and run in a tangential direction. These remarks 
apply to the lower region of the stem ; in the upper portion 
no second zone of anomalous thickening is usually distinguish- 
able, and the first ring, as also the normal vascular zone, is 
much less strongly developed. 
In conjunction with the second anomalous ring the same 
phenomenon of inverted cambial activity occurs, but here in 
a more easily distinguishable and clearly defined manner. 
On the inner side of several of the segments, and separated 
from them by a few layers of parenchyma, appeared a bundle 
or segment, usually of smaller size, with inverted orientation, 
so that its xylem was placed directly opposite that of the 
normally orientated segment in some cases, while in others the 
bundle lay obliquely and at an angle with the other (Figs. 2, 10). 
The elements composing these inverted segments are not 
always so well developed and their walls not so sharply defined 
as those of the main segments, facts which tend to make them 
insignificant in appearance and easily passed over. Such 
a bundle was sometimes represented by only a mere rudiment 
made up of a few elements. In one or two cases, where the 
inverted segment lay rather obliquely, it formed an almost 
continuous zone with the normally orientated segment, thus 
indicating a tendency towards the formation of a concentric 
