N. E. Stevens — New Jersey Palmoxylon. 



429 



follows: The outer, limiting layer is composed of cells with 

 cuticularized, comparatively thin, walls. It does not neces- 

 sarily form a perfectly regular sheath. The outer cortex 

 (p. 432) is a tegumentary system consisting of several layers of 

 elongated, lignified, and more or less pitted cells. The inner 

 cortex (p. 434) is composed of three "zones"; an outer zone 

 usually without* air spaces, a hroad middle zone with large air 

 spaces, and an internal zone of regular cells. The middle zone 



Fig. 13. 



Fig. 14. 



Fig. 13. Inner portion of cortex of large root, showing endodermis (E), 

 and part of the inner cortex, the inner zone of which (I) is composed of three 

 layers of thin-walled cells. In the middle zone of the inner cortex are shown 

 large intercellular spaces and the heavier lignified stone cells (A), x 70. 



Fig. 14. Outer portion of cortex of same root as shown in fig. 13, showing 

 outer cortex (0 shaded), outer zone of inner cortex, and a portion of the 

 middle zone of the inner cortex, x 70. 



shows considerable variation in the shape, size, and number of 

 the air spaces as well as in the number of cell layers separating 

 these spaces. The endodermis (p. 438) consists of a single 

 layer (sometimes locally doubled) of lignified cells from three 

 to six times as long as they are broad. 



With the exception of the " limiting layer " these same 

 regions were readily distinguishable in the present fossil 

 specimen. Figures 13 and 14 were taken from the cortex of 

 a fully developed root, fig. 13 being, of course, the inner and 

 fig. 14 the outer portion. The photomicrograph, fig. 15, 

 will give an idea of the relative size of the various zones of the 

 inner cortex. 



