272 
DOUGLAS HOUGHTON CAMPBELL 
Except for the apex, which as we have seen has a conspicuous 
beak formed of several (8-10) layers of cells, the capsule wall is usually- 
composed of three layers. In the earlier stages these layers are com- 
posed of uniform cells, but as development proceeds the two inner 
layers undergo more or less numerous divisions while the cells of the 
superficial layer remain undivided and increase much in size as the 
capsule enlarges. On the walls of the two inner cell-layers charac- 
teristic thickenings are formed while the walls of the superficial cells 
undergo little change. The thickenings on the walls of the inner cells 
are of various kinds — ridges, complete rings, half-rings, and spirals. 
Grun states that these cells contain chlorophyll and starch granules. 
The ripe capsule is ovoid in outline, and not globular, as Andreas 
states. It opens by four short and somewhat irregular valves. Griin 
examined the ripe spores and elaters. The former have reticulate 
thickenings upon the surface, and resemble the spores of certain 
species of Pallavicinia. They measure from 20 to 2^ fi in diameter. 
The elaters reach the extraordinary length of 1,250 fi. 
Conclusion 
Most writers agree that Treubia has much in common with the 
acrogynous leafy liverworts and in a sense connects them with the 
typical anacrogynous forms. Among the latter, the genera Fossom- 
bronia, Ptalophyllum and Noteroclada are most nearly related to 
Treubia. Cavers^^ in his recent summary of the Hepaticae considers 
these to have been derived from Pellia-like ancestors, but he looks 
upon Fossombronia as most nearly related to the Acrogynae. 
It seems more likely that Treubia is nearer to the Acrogynae than 
is Fossombronia. This is true of the character of the leaves, the 
apical cell, and the groups of archegonia. It is by no means impossible 
that the dorsal scales may be the homologue of the dorsal lobe of such 
leafy liverworts as show a bilobed leaf, e. g., Madotheca, FruUania, 
etc. Schiffner,^*^ who has studied Noteroclada concludes that it is 
closely related to Treubia and must be considered as the end of a 
series of which Fossombronia is a lower member. 
Fossombronia differs a good deal from the Pellia type, and is in 
1^ Cavers, F. The Inter-relationships of the Bryophyta. New Phytologist 
Reprint, No. 4. Cambridge, 191 1. 
16 L. c. 
