Evans: NOTES ON GENUS HERBERTA 201 
ad 
The bands of thickening just described soon become united by 
median bands laid down on the free walls (TEXT FIG. 12). These 
leave a series of thin places on each side, which show at first 
angular outlines. Almost simultaneously the bands on the vertical 
walls increase in thickness and become connected by deposits laid 
down between them, the result being that these walls acquire a 
od 
a8 = S 
+ SS 
ala 
x L 
ees, % C. 
12 ZY; 13 
Fics. 11-13. HERBERTA JUNIPERINA (Sw.) Trevis. 
tr. Very young cell from the basal vitta of a leaf, surface view, X I,000. 12. 
Somewhat older cell from same vitta, surface view, 1,000. 13. Still older cell 
from same vitta, optical section, X 600. The figures were all drawn from speci- 
mens collected by L. M. Underwood along the trail from Cinchona to Morce’s Gap, 
Jamaica, 280. 
continuous layer of thickening except for an occasional pit. At 
first the original bands are thickened more conspicuously than the 
intermediate regions and the vertical walls appear distinctly 
scalloped when examined in optical section (TEXT FIG. 13). But 
the conditions just described are temporary. The thin places in 
the free walls are gradually filled up by deposits of thickening, 
becoming rounded as they diminish in size, and the depressions 
between the scallops along the vertical walls become obliterated 
