On the Structure and Biology of Fegatella conica. 
BY 
F. CAVERS, B.Sc., 
Lecturer in Biology Municipal Technical School , Plymouth . 
With Plates VI and VII and five Figures in the Text. 
HE genus Fegatella Raddi ( Conocephalum Wiggers) is represented by 
X two species, of which one, F. conica , is very widely distributed in the 
North Temperate Zone, whilst the other, F . supradecomposita, is confined to 
Japan and China. 
F. conica , which is fairly common in Britain, is one of the largest of 
the thalloid Hepaticae, the broad dichotomously branched thallus sometimes 
reaching a length of six inches (1 5 cm.) or even more ; the older parts 
gradually die down as the new branches creep onwards over the substratum, 
which often becomes covered by a continuous layer of these plants, 
extending over several square feet. The plants grow chiefly in moist 
situations, especially on stones beside shaded streams, and sometimes 
become entirely submerged in water. This species was named Hepatica 
fontana by Micheli in 1729 ; the generic name, which was given on account 
of a supposed resemblance between the branched thallus and the lobes 
of the liver, was after Micheli’s time applied to the whole group ( Musci 
hepatici , Hepaticae), 
The upper surface of the thallus is marked by lines dividing it up 
into polygonal (mostly hexagonal) areas and forming an extremely regular 
network. Each of these areas corresponds with an underlying air-chamber, 
and has in its centre a light spot which stands out in sharp contrast with 
the dark green colour of the thallus and marks the position of a pore. 
The central portion of each area is raised so that the pore occupies the 
summit of a low cone. When water is placed on the upper surface of 
the thallus, it collects along the lines separating the air-chambers and 
is quickly drained off by means of this network of channels. 
In neither Marchantia nor Lunularia , which have a general external 
resemblance to Fegatella , is the areolation of the thallus so definite as in 
the latter genus, which is therefore readily distinguished from the other 
commonly-occurring genera of the Marchantiaceae, even when no repro- 
ductive structures are present. Another characteristic feature of Fegatella 
[Annals of Botany, Vol. XVIII. No. LXIX. January, 1903.] 
