1919} Evans,— Notes on New England Hepaticae,— XV 167 
section cut from the Oakes Gulf material the outermost layer showed 
eighteen cells, the second twelve and the innermost seven. It is 
evident, therefore, that the stalk belongs to Douin’s “type général,” 
agreeing in this respect with N. hyalina and N. obscura. The cells 
of the capsule-wall are much like those of N. hyalina. Those of the 
outer layer average about 55 X 20 u, and the thickenings in the trans- 
verse walls are infrequent; those of the inner layer average about 11 u 
in width and usually measure 40-70 uw in length. These measurements 
are slightly different from those given for N. hyalina, but the measure- 
ments of the spores and elaters are essentially the same in the two 
species. 
Some of the differences between N. obovata and the two preceding 
species have already been brought out in the above discussion. In 
distinguishing it from N. hyalina the very unlike habitats should be 
borne in mind, N. hyalina preferring sandy banks and N. obovata 
damp or wet rocks. The differences in habit and in color are likewise 
significant, N. hyalina being usually prostrate, adherent to the sub- 
stratum and pale, while N. obovata tends to be ascending, free from 
the substratum and dark. The plants are further remarkable for 
their curious turpentine-like odor, although this peculiarity is found 
also in N. obscura. In distinguishing N. obovata from this latter spe- 
cies, which likewise grows on rocks, the larger size, the lack of a purple 
pigmentation, the more exerted perianth, the less elongated cells of 
the same and the lobulate mouth will prove especially helpful. Per- 
-haps the paroicous inflorescence, which distinguishes N. obovata from 
both these species is the most important of its differential characters. 
This character, however, is shared by several other species of Nardia 
and also by Jungermannia sphaerocarpa and its allies. Fortunately 
there is little danger of confusing N. obovata with many of these paroi- 
cous species. The only ones which approach it closely are N. paroica 
and N. subelliptica, which need not be considered further at the 
present time. 
The great variability of N. obovata is wel described by C. Jensen,! 
in connection with its occurrence on the Faroe Islands.: “Near the 
coast," according to his account, “the small forms — fruiting abund- 
antly during spring — are frequent in crevices and on the ground 
among rocks. In the mountains the plants gradually become stouter 
1 Bot. of the Faeróes 1: 135. 1901. 
