166 MR. E. S. SALMON ON THE GENUS NANOMITRIUM. 
There remains, now, only .N. megalosporum to be considered. 
Here, also, there is no trace of a rudimentary lid (fig. 10). 
Moreover, from the study of authentic specimens (Musci 
Appal. 47), I have come to the conclusion that this species does 
not belong to Nanomitrium. 
Philibert (5. p. 56) remarks that in this species an approach is 
made in the leaf-areolation towards Ephemerum, but considers the 
plant to be a true Nanomitrium for the following reasons :—“ La 
structure du fruit est bien celle du genre Nanomitrium. La calyp- 
tra est réduite au style, auquel adhérent quelquefois deux ou trois 
petits lambeaux irréguliers ; la capsule est tout à fait sphérique, 
... sa surface supérieure est arrondie ou un peu déprimée, sans 
aucune trace de pointe. . . L'enveloppe capsulaire. . . est toujours 
formée . . . d'une seule couche de cellules hexagonales...Il n'y 
a point en réalité de sporange ni de columelle; et cette espèce 
reste toujours bien séparée par là du genre Ephemerum, dont 
elle s’éloigne d'ailleurs par sa capsule uniformément arrondie, 
par l'absence des stomates, par l’imperfection de sa coiffe, et par 
son inflorescence synoique.” My observations do not confirm, 
in the most important points, those of Philibert's. 
In the first place, these specimens showed stomata on the 
capsule. The stomata, although few in number, appear to be 
always present; they occur on the upper half of the capsule 
(figs. 10 & 11), and are exaetly similar to those found in 
Ephemerum, e. g. E. serratum, Hampe. The capsule-wall con- 
sists of more than one layer of cells, and the spore-sac is easy 
to observe in almost ripe capsules. I consider, therefore, 
that this species should be called Hphemerum megalosporum. 
I was not able to see the calyptra. Philibert, as we have seen, 
considers it right for the genus Nanomitrium; but on the other 
hand Sullivant (7. fig. 7 of pl. xi.) figures it as certainly better 
developed than in tenerum, synoicum, and Austini. If the plant 
is allowed to be an Ephemerum, we must regard it, by reason of 
the rounded capsule and rudimentary calyptra, as a connecting 
link with Nanomitrium. 
Wemay here consider what have been stated to be the essential 
characters in which Nanomitrium differs from Ephemerum. Austin 
(1), in founding the genus, relied on the calyptra and inflorescence. 
Lindberg (2) remarked: * Ex Ephemero ... distinguitur his 
notis maximi momenti : foliis laxis et difficile emollitis, canalicu- 
latis, superne interdum latioribus, obtuse serratis, omnino enerv. 
ibus, edificatis a cellulis conformibus, levissimis et duplicem 
