300 
F. Cavers. 
(in some species absent), the archegonia are developed on the 
main shoots, the perianth is cylindrical and free from the 
involucre. From Lophozia we can trace three main lines. (1) One 
line leads directly through Sphenolobus to the Scapaniaceous genera 
Diplophyllum and Scapania, in which the leaves are deeply lobed, 
the upper lobe being smaller than the lower and the insertion 
succubous. (2) A second line leads through a long series of 
genera with relatively simple characters ( Plagiochila , Lophocolea, 
etc.) to genera to in which the archegonia are shifted on to short 
lateral branches ( Chiloscyphus , Harpauthus, etc.), and which in this 
and other respects form a transition to the Cephaloziaceae through 
intermediate types like Cephaloziopsis, Cephaloziella,, and Cepha- 
lozia itself. Several marsupial genera arise from this line, e.g., 
Tyliinanthus and Acrobolbus, which are allied to Plagiochila , and 
Saccogyua which resembles Harpauthus in vegetative characters. 
(3) The third line is marked by the reduction in size of the 
perianth, fusion of perianth with involucre, and the development 
of marsupia; this line begins with Marsupella, and leads through 
Nardia to the marsupial genera Southbya, Calypogeia, Lethocolea, 
etc. 
In the Cephalozia series, three lines start from Cephalozia 
itself. (1) One of these is marked by more or less far-reaching 
reduction of the leaves, leading to forms like Zoopsis and Pterop- 
siella, the latter becoming thalloid owing to the “fusion” of the 
leaves with the stem, while Protocephalozia has a persistent 
filamentous protonema, leaves being produced only on the sexual 
shoots. (2) A second line, in which the leaves are only slightly 
lobed or quite entire and the archegonia are restricted to very 
short ventral branches, leads through Odontoschisma and Ade- 
lantlius to the marsupial genera Marsupidium and Kantia —the only 
marsupial forms in the Cephaloziaceae. (3) The third line, 
characterised by the division of the leaf into increasingly numerous 
and deep lobes, leads through B izzania and Lepidozia to Arach- 
niopsis and Telaranea, which closely resemble the Ptilidiaceous 
genus Blepharostoma and form a transition to this family. 
The Ptilidiaceae, though a small family, shows several diverging 
lines of development, all of which appear to end blindly. In the 
majority of the genera, the archegonial group is terminal on the 
main axis; in the others ( Ptilidium , Lepicolea, Mastigophora , 
Isotachis ) it is on a short branch, but this is lateral—not ventral, 
as in the Cephaloziaceae. A very marked character of the family 
