x smaller leaf of different form and tissue, nothing more or less, 
nee moon 
An undescribed structure in Mnium, with notes 
on the genus Orthomnion. 
Among some mosses recently received from India was one rh 
which I recognized as identical with #nium (Orthomnion) cris- 
pum Mitt. In the course of examination [ noticed some small foliar 
appendages to the stoloniform or creeping stems, entirely diffe- Le 
rent from the true leaves, and more resembling the amphigastria 
of certain mosses and hepaticae. These I supposed at first to be 
abnormal. rudimentary leaves; but closer examination showed 
them to be constantly present, on both the creeping shoots and 
the erect o and à stems. Their irregular arrangement, inserted 6 ë 
on all sides of the stem and irrespective of the position of the < 
true leaves, showed them not to be of the nature of amphigastria, Ps 
and they are perhaps better termed accessory leaves. Further 
examination of these structures, and comparison with other species 
of Mnium, led to some observations which it seems worth while 
to put on record here. à Sie A 
If the growing point of one of the creeping, sterile shoots of 
Mnium affine be examined, the young, rudimentary leaves will 
be seen to be all similar, erowded together, ovate-acuminate, 
with the areolation immature and quite undifferentiated into bor- 
der and lamina, except at the extreme apex of the leaf, where at 
a quite early stage elongate hyaline cells are formed, constituting 
a strong acute point to the leaf. If the process of development be 
followed (or, which comes to the same thing, if the stem be exa- 
mined further and further back trom the growing point), it will 
be seen that the development of the leaves for the most part takes 
placeregularly; astheinternodes lengthen the leavesrapidlyenlarge, 
“the cells increase in size, beginning with those at the base, the 
border cells are gradually differentiated, and with the increase in 
growth of the cells the leaf becomes wider, obovate or sub-orbi- 
cular, the acute point of the immature leaf remaining almost 
“unmodified and becoming the apieulus of the mature leaf. 
If several of these stoloniform stems be examined, one is sure 
to see here änd there among the fully developed leaves, a much 
in fact, than an immature leaf which has failed to develope, an 
infant among adults. The arrestment of growth may take place at 
different stages ; the cells may remain minute and thin-walled, the 
marginal searcely distinct, or (hey may have atlained a pretty 
nearly normal size, with a clearly differentiated border ; but the 
leaves always agree, s0 far as I have observed, in relaining the 
