New and Little Known West-Himalayan Liverworts. 3 19 
growing points again show signs of forking. The receptacle has 
ordinary simple pores between the antheridial papillae, like those 
of the thallus but the female receptacle, which is slightly concave 
on the dorsal side when mature, has a well-developed assimilating 
tissue with barrel-shaped pores (Fig. 6, b). The most important 
feature of the plant, however, is that the receptacle is not two- or 
three-lobed as described by Stephani, but may have as many as 
nine lobes. Five or six involucres in one receptacle are most 
commonly met with (Fig. 5, b). Two or three carpocephala may 
arise, one after the other, on the dorsal side of the thallus. Similarly 
three antheridial receptacles may be formed, one after the other, 
on a separate lobe of the thallus which has no carpocephalum, or a 
carpocephalum may be formed in front of the male receptacle. An 
interesting feature in connection with the female receptacle is the 
Fig. 6. Plagiochasma appendiculatum (a, b, c) and P. articulatum (d, c) : a, 
horizontal section of involucre, x 50 ; b, stoma from female receptacle, x 200; 
c, vertical section of operculum, x 200 ; d, ventral scale, x 15 ; e, transverse 
section of peduncle, x 15. 
“ estivation ” of the valves of the involucre. The valves are folded 
in a peculiar manner in the present species, P. articulatum, to be 
described next, and another species (P. Aytonia), three species 
which were examined. The margins of the young involucre are 
bent inwards at first, but as the capsule increases in size, they are 
pushed to one side (Fig. 6, a) so that they press against the inner 
surface of the wall of one of the valves. Later on one margin 
becomes perfectly free while the other remains permanently folded 
along the inner surface. The process is illustrated in the accompanying 
