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This moss is considered to be distinct from H y pn um H a lleri,
by every authörj' with the single exception of Professor
S c h w a e g r i c h e n . There are, indeed, it must be confessed,
several species of the squarrose-leaved division of Hypnwm,
which are difficult to define by written characters, and yet are
never liable to be confounded Yfith each other, when they are met
with either in herbaria or in their native places of growth.
Two of these species we have named; and that they a re entitled
to the rank of species, no one it is presumed can doubt,
who sees them witb the naked eye. Their principal discrepancies
seem to exist in their habit, their stems and leaves.
In H . H a lle ri, the stems are creeping, and pretty regularly
pinnated. In H dirmyrphwm, they are never creeping, and
very irregularly pinnated. The ramuli of the former have always
recurved acuminate leaves: those of the latter are always
imbricated, and never acuminate, besides which, the ramuli are
generally much attenuated, a character that does not occur in
the other. I shall not dwell upon any evidence to be derived
from the nerves, which are notoriously variable in several
species of this division. In my specimens there are two
distinct ones. B r i d e l and S c h w a e g r i c h e n say there is
scarcely any or even none at all. Again, the precise shape of
the leaves of the ramuli is not to be relied on. I found them to
be simply acute, exactly as is represented in V o i t ’s H . squar-
rulosum, (S t u r m ’s Deutschlands Flora). It is worthy also of
observation, that B r i h e l says the leaves of our plant are very
entire, whereas I find them serrulate, the serratures ceasing
where the acumination commences, as in V o i t ’s plant. On
the other hand, H . H a lle r i is said to have serrated leaves,
whereas all my specimens have them very entire. The last-mentioned
species I hope to be able to figure in an early number, as
I had the good fortune to find it in an excursion to Ben Lawers
two years ago, made along with my friends Dr H o o k e r and
the discoverer of the present moss.
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Fig. 1. H . dimorphum, nat. size. Fig. 2. A portion o f the stem, with ramuli.
Fig. 3. L e a f o f the main stem. Fig. 4. L e a f o f the ramuli. Fig. 5. L e a f
from the summit o f the main stem. Fig. 6. Perichcetium, fruitstalk, and capsule,
with the lid. Fig. 7. Portion o f the outer peristome. Fig. 8. Portion o f
the inner ditto. Fig. Q. Sporules.— A ll except Fig. 1 . more or less magnified.