814 ON NAIAS GRAMINEA DEL., VAR. DELILEI MAGNUS. 
compare them with the slightly different figure of Braun on Plate 
251, fig. 10. 
For drawings of the leaf-sheaths of Naias minor and N. major see 
Plate 251, figs. 9 & 29, and compare the former with Braun’s figure, 
Plate 251, fig. 11. 
y 
i Sf 4 
Oa 1G 
My oe SxeN 
SS Ca se 
> 
2 
pet 
In N. flewilis (fig. 59) the cells are more loosely aggregated also, 
but the line of — cells, though not so well-defined as in the 
amina, 1s more clearly ag. it is in N. graminea. 
cells of the sheath, as WOR ca the, a d i 
N. flexilis are larger and longer than they are in N. graminea ; bu 
the two species may be distinguished by the length of the imbedded 
portion of the spine, which in N. flexilis is less, and in N. graminea 
is more, than one-third of its free length. The leaf-cells of NV. flewilis 
generally are larger than those of NV. graminea (compare figs. 45 and 
46 with figs. 47 to 49, and fig. 58 with fig. 59, all of which are 
drawn to the same scale), 
VITI.—Lear-structTuRE. 
The anatomy of the leaves of N. gramineais simple. The margins 
of the lamina to the extent of one-third the breadth are composed of 
two layers of cells (see figs. 68 and 65), which in the Reddish 
specimens do not present that contrast in the size of the of 
