MR. E. 8. SALMON ON THE GENUS NANOMITRIUM. 163 
Notes on the Genus Nanomitrium, Lindberg. By Ernest 
STANLEY SALMON. (Communicated by J. G. BAKER, F.R.S., 
F.L.S.) 
[Read 2nd February, 1899.] 
(Prate 5.) 
In 1870 Austin (1) published the name Micromitrium as a 
genus for three American Ephemeroid mosses (JM. Austini, 
M. synoicum, and M. megalosporum), with the following diag- 
nosis: “ Capsula globosa, immersa, tenera, apiculata vel mutica, 
clausa, vel pressa in medio horizontaliter fatiscens, brevissime 
pedicellata vel exacte sessilis. Calyptra minima, subdisciformis, 
stylidifera, arcte adherens. Flores synoici. Plante . 
Ephemera valde referentes distincts tamen calyptre forma et 
minutie ; inflorescentia &e.” 
In 1874 Lindberg (2) pointed out that Austin's name must 
give way to the previously published Micromitrium of Spruce, 
and substituted the name Nanomitrium, at the same time adding 
to the genus Ephemerum equinoctiale, Spruce, from the Amazon, 
and the European E. tenerum, Hampe. The last-named species 
is very rare, and since its original discovery by Breutel at 
Niesky, Germany, about 1837, has only occurred sporadically 
in a few places on the Continent. Mitten discovered it 
in England (Hurstpierpoint, Sussex) in 1854; and it then dis- 
appeared until 1896, when Mr. W. E. Nicholson found specimens 
near Crowborough, Sussex (see Journ. of Bot. 1896, p. 479). 
A few months ago Mr. Nicholson kindly sent me some fresh 
plants. On examining the capsules of these specimens of Nano- 
mitrium tenerum, I found that certain cells of the wall (which is 
only one layer thick at maturity) were differentiated in such a 
way that the capsule possessed a well-marked rudimentary lid. 
The position and relative size of these differentiated cells, 
which form a complete zone round the capsule, can be best 
seen by reference to Pl. 5. figs. 1 & 2, which were drawn from 
Mr. Nicholson's Sussex specimens. 
The occurrence of a rudimentary lid in Nanomitrium tenerum 
is interesting, as Philibert (5), who lately critically examined the 
five species of the genus, does not mention any such structure. 
Limpricht (6) also, in giving the characters of the Order iu which 
he places Nanomitrium, says: “ Kapsel...stets ohne Andeut- 
ung eines Deckels." 
LINN. JOURN.—BOTANY, VOL. XXXIV. N 
