F. Cavers. 
170 
rest of the scale by a deep constriction ; the appendages of the 
younger scales curl upwards over the growing-point (Fig. 26). 
The male receptacles are sessile in the lower genera. The 
simplest type is seen in Exormotheca, where the antheridial 
chambers are developed in a zigzag row along the middle of the 
thallus. In Lunularia the receptacle has the same structure as in 
Fig. 26. Fegatella conica. Growing point from above, showing the reflexed 
scales and the areolation of the thallus. x 10. 
Reboulia ; the antheridia, which are developed in acropetal suc¬ 
cession, are peculiar among Marchantiales in having a long slender 
stalk. In Wiesnerella, Fegatella, and Dumortiera, the receptacle 
evidently represents a branch-system, since the antheridia are 
(especially in Fegatella ) clearly arranged in several radiating rows. 
In Bucegia, Preissia, and Marchantia, the receptacles are definitely 
radial and lobed (palmate in some species of Marchantia), with a 
zigzag row of acropetally developed antheridia to each lobe, and the 
receptacle is raised above the thallus on a stalk with two furrows; 
here the receptacle is undoubtedly a branch-system, having as many 
growing-points as there are lobes. 
The carpocephala vary considerably in structure, but in all 
cases they are terminal on the thallus and each involucre contains 
a group of archegonia, except in Fegatella where there is but one 
archegonium as a rule. The simplest carpocephalum is that of 
Exormotheca, which has two involucres, standing right and left; 
the central tissue above and between the involucres is little 
developed, as in Clevea and Plagiochasma, but the stalk has a furrow 
and the involucres contain several archegonia. Lunularia is 
exceptional in that the carpocephalum stalk has no furrow, but in 
