1912] Evans,— Notes on New England Hepaticae,— IX , 9 
name, are not numerous. They are mostly confined to the margin 
but a few sometimes appear scattered over the upper surface. Those 
on the margin occur singly or in pairs. The cilia are whitish and 
usually sharp-pointed and have a length of 0.07-0.15 mm. In cross 
section the lower surface appears more or less convex in the median 
region, while the sides rise obliquely and meet the upper surface at a 
sharp angle of about 60 degrees. The thickness of the thallus is 
from one third to two thirds as great as the width. The epidermis 
is much the same as in R. arvensis. 
The species has a monoicous inflorescence and produces an abun- 
dance of capsules, which show more or less clearly through the translu- 
cent tissue above them. The mature spores are brown and measure 
85-100 « in maximum diameter. At the junction between the convex 
face and the three plane faces a narrow wing 5 u or less wide is devel- 
oped, and this wing is indistinctly erenulate and very minutely verru- 
culose. The convex face is covered with a regular reticulum, the 
meshes numbering about seven across the diameter and measuring 
about 12 » in width. At the angles of the meshes the bounding 
ridges project as short and rounded protuberances. On the triangular 
faces of the spore the ridges are lower than on the convex face; they 
sometimes form an incomplete reticulum but are usually vermicular 
and unconnected. 
Although a strong superficial resemblance exists between R. hirta 
and R. arvensis it is not difficult to distinguish them. The cilia of R. 
hirta afford the most striking difference, the thallus of R. arvensis 
being usually smooth throughout. European writers, however, have 
shown that cilia oecur exceptionally in species which are usually 
smooth and that they are sometimes absent in species which are 
usually ciliate. It is therefore unwise to emphasize too strongly a 
difference derived from the presence or absence of cilia alone. For- 
tunately A. arvensis and R. hirta show other differences of a more 
trustworthy character. In R. arvensis, for example, the upper sur- 
face of the thallus bears a broad median groove, while in R. hirta 
it usually bears a narrow sulcus only. R. arvensis is further distin- 
guished by its slightly smaller spores, reticulate on all four faces; in 
R. hirta the reticulum is usually distinet on the convex face only. In 
R. trichocarpa, according to Howe, the spores are more opaque and 
slightly larger than in R. hirta, the margins of the thallus are rounded 
rather than acute, and the cilia are much more numerous and longer, 
attaining a length of 0.3—0.65 mm. 
