154 Rhodora [SEPTEMBER 
rarely vaguely emarginate, and the margin is quite entire. At the 
dorsal base there is usually a narrow but distinct decurrent portion, 
but this is sometimes scarcely evident; it is especially marked when 
the margin shows an abrupt turn just above the region of decurrence. 
Although the leaves tend to spread widely from their long lines of 
attachment, they are sometimes more or less concave and then often 
assume an ascending or suberect position, the leaves of one side thus 
approaching those of the other. On vigorous plants the leaves tend 
further to be undulate, and this condition is usually best marked in 
the upper leaves of a female branch and in the bracts themselves. 
This is well shown in the figures published by Maevicar and Müller.! 
As Schiffner has shown, the species of the subgenus Eucalyx exhibit 
wide extremes in the size of their leaf-cells (Figs. 4-8), and these 
extremes sometimes manifest themselves in the different leaves of an 
individual plant. Specific differences based on differences in the size 
of the cells must therefore be used with caution. The five specimens 
_of N. hyalina distributed by Schiffner in his “ Hepaticae europaeae 
exsiccatae" (Nos. 62, 63, 367, 368, 369), and coming from widely 
scattered localities, gave the following average measurements: mar- 
ginal cells, 23-34 u; median cells, 32-41 X 26-34 u. These measure- 
" ments agree essentially with those obtained from North American 
specimens, although one of the latter showed marginal cells ranging 
from only 15 u to 28 u. Except for a slight difference in size the 
marginal cells are like the others, and the leaves consequently lack 
the specialized border which forms so distinctive a feature in N. 
crenulata (Sm.) Lindb., N. crenuliformis (Aust.) Lindb. and certain 
other species of the subgenus. Another feature which will help in 
distinguishing the species from N. crenulata is the constant presence 
of trigones. These are usually distinct, even when minute, and are 
often conspicuous with bulging sides. In fresh material the oil 
bodies in the cells stand out clearly but cannot often be detected in 
dried specimens. Each cell contains from two to eight of these bodies, 
which are oval or bluntly fusiform and measure 10-14 y in length and 
9-6 u in width. They have even outlines but present the appearance 
of being minutely granular in structure. According to Stephani ? 
the cuticle of N. hyalina is papulose, but most authors describe it as 
smooth and thus distinguish it from the striate-verruculose cuticle 
1 Rabenhorst's Kryptogamen-Flora 6: f. 272. 1909. 
? Bull. de l'Herb. Boissier II. 1: 502. 1901. 
