New and Little Known West-Himalayan Liverworts. 323 
It appears, therefore, that the dorsal position of the sexual 
receptacle has appeared at various levels independently. Two such 
cases have been mentioned. (1) At the level of Exormotlieca, 
Stcpliensoniella has diverged to one side and leads to forms like Boscliia 
and Corsinia. (2) At the level of Reboulia, Plagiochasma has been 
given off. It may be supposed that Corsinia has arisen from some 
form like Plagiochasma owing to the similarity of the structure of 
the capsule wall, but the structure of the elaters and the highly 
organised sexual receptacles are against this view. Then, again, 
we know no transitional forms between the two genera. (3) 
Monoselenium presents a third case. (4) Preissia commutata , which 
still has a well-developed composite female receptacle with two 
rhizoid furrows in the carpocephalum stalk. These are the four 
important examples showing the origin of a dorsal carpocephalum. 
In the case of Stephensoniella , Monoselenium , and probably Preissia, 
the growing point produces several archegonia in succession, though 
in Preissia Stephani 1 states that the archegonia are transversely 
(and not at all longitudinally) inserted. 1 In Plagiochasma, and the 
Operculatae and Astroporse in general, the growing point produces 
usually a single archegonium though in some species of Fimbriaria, 2 
Sauteria 3 and Peltolepis 3 each involucre often contains more than 
the archegonium. In an undetermined species of Fimbriaria from 
Mussoorie the writer also found two sporogonia in one involucre in 
several cases, but in these cases it was clear that the intervening 
walls of two involucres lying side by side had not developed owing 
to the great proximity of the sporogonia, as a rudimentary septum 
was found between the two and the latter were also arranged 
transversely. 
1 Species Hepaticarum,” p. 154. As shown by Leitgeb (“ Untersuchungen 
iiber die Lebermoose,” Heft. 6, p. 109) and by Cavers (“Contributions to the 
biology of the Hepaticse,” p. 32), the archegonia in each involucre in Preissia 
are developed in the same centripetal succession as in Marchantia. “The 
archegonia begin to arise before the branching of the young receptacle is 
completed ; each of the growing points undergoes division while the archegonia 
are being formed, and as the receptacle is growing out in four radiating lines, 
the archegonia become arranged in tangential rows ” (Cavers, loc. cit.). 
2 Campbell, “ Mosses and Ferns.’’ 
3 Cavers, “ Inter-relationships of the Bryophyta,” p. 37. 
