was preparing its description tor publication, I was surprised
to find, among otlier specimens rvhich liad arrived from its
intelligent discoverer, all the mature calyptrse to be unequivocally
dimidiate: in the young state alone do they retain
their mitriform character. The species, however, is so decided
ly a Grimmia in every other respect, that it would be highly
injudicious to exclude it, on account of the ultimately dimidiate
calyptra, though, in the present state of the science, we must
be swayed more or less by artificial characters.
In general appearance, Grimmia unicolor approaches to
T t ichostomum ellipticum, but it bears the nearest resemblance
to T. microcarpum, for which it might he passed over even by
experienced botanists. On the Clova Mountains, it seems far
from rare, as Mr D r u m m o n d , in a second excursion, found it
plentifully. In fruit it is not so frequent.
A ll the specimens I have seen, produce occasionally very
slender filiform shoots, imbricated with leaves of a different
form from those of the main stem and branches. One of these
I have introduced into the accompanying plate, with a magnified
representation at Fig. 6.
Figs. 1 . & 2. Grimmia unicohr, nat. size. Fig. 3. A plant magnified. Fig. 4.
Lower leaf. Fig. 5. Upper leaves. Fig. 6. Leaves belongins to the filiform
shoots above alluded to. Fig. 7. Theca. Fig. 8. Lid. Fi^. 9. Portion o f
the peristome.