164 MR. E. 8. SALMON ON THE GENUS NANOMITRIUM. 
As it seemed just possible that the occurrence of these cells 
might be due to an individual variation, and not normal for the 
species, I examined original specimens collected by Breutel, in 
Schimper's Herbarium, as well as Husnot's Musci Gall. no. 801, 
and Mitten's Hurstpierpoint plants—all in the Kew Herbarium. 
Without exception, the capsules of these specimens possessed 
the zone of differentiated cells. 
The constant presence of a rudimentary lid in N. tenerum led 
me to examine the other species of the genus, in order to 
ascertain whether it should be considered a generic or specific 
character. The remaining species are N. synoicum, N. Austini, 
N. equinoctiale, and N. megalosporum. In N. synoicum the 
rudimentary lid is very well defined; and although I was not 
able to find any opened capsules, I am inclined to think that a 
complete separation of the “lid” takes place in nature. 
All the ripe capsules that were examined opened on the 
slightest pressure along the line of narrow cells (Pl. 5. fig. 3), the 
upper part of the capsule coming away like a true lid. More- 
over, 1 believe that the narrow cells, in which the dehiscence 
occurs, are instrumental in bringing about the detachment of the 
“id.” 
At maturity the cell-walls of this layer are extremely thin and 
slightly disorganized, so that the vertical septa are no longer 
visible (Pl. 5. fig. 4). When, on slight pressure, the capsule-wall 
ruptures, and detaches the regularly circular “ lid,” portions of 
these very thin cell-walls of the differeutiated zone are found 
attached partly to the “ lid ” and partly to the mouth of the cap- 
sule. In N. Austini (Pl. 5. fig. 5), also, we find that the capsule 
possesses the same structure. 
Philibert (5. p. 51) has mentioned the regular dehiscence of the 
capsule of N. tenerum in the following words: “ La capsule... 
semble plutôt se déchirer sur place, quelquefois irréguliérement, 
mais souvent aussi suivant une ligne circulaire qui la partage en 
deux hémisphéres égaux, le supérieur se séparant en forme de 
calotte réguliére." 
In Austin's original generic description (^ capsula ... pressa in 
medio horizontaliter fatiscens ") the same character is indicated 
and the regular dehiscence has even been figured by Sullivant (7), 
at fig. 6 of his plate of N. Austini. The presence of a zone of 
specialized cells satisfactorily accounts for the regular dehiscence 
which has been observed by the different authors quoted above. 
