Calobryum Blumei, N. ad E. 1 1 
more than one layer of cells. Of the Marchantiales, probably Monoclea 
most nearly resembles Calobryum in the elongated form of the capsule 
as well as the long seta. 1 
As the development proceeds, there is the usual differentiation of the 
archesporial tissue into the spore mother-cells and elaters ; but no definite 
relation of the two to each other could be detected, nor was any structure 
recognizable as an elaterophore. The spore mother-cells are often in rows 
of two to four, lying between the elongated young elaters. Both spore 
mother-cells and elaters show a definite but very delicate membrane, within 
which lies the contracted protoplast (Text-fig. 6 , G). 
The apical portion of the capsule wall is thicker, and finally forms 
a conspicuous prominence or beak, much like that of Pallavicinia or 
Podomitrium (Text- fig. 6, D). 
No specimens could be found showing the final nuclear divisions of the 
spore mother-cells, and in nearly all cases the spores were already free. In 
the only case where the spore tetrads were seen (Text-fig. 6, H) there had 
apparently been two successive divisions resulting in the bilateral type 
of spore ; but of the four young spores only one contained a normal nucleus, 
the nuclei of the other three having disintegrated. Whether this appearance 
is normal is a question ; but it may be that only one spore of the tetrad 
reaches maturity. The ripe spore (Fig. 8) appears quite globular, as might 
be expected in case only one spore of a tetrad developed. Further study 
of spore development will be necessary to decide this question. 
The ripe spore has a moderately thick membrane, and the surface 
is marked by numerous short, blunt prominences. The long, slender 
elaters have a double spiral (Fig. 7). 
A very massive calvptra is devlloped, which finally may reach a length 
of 1 5 mm., while the seta is two or three times as long, and bears at its tip 
the slender pointed capsule, about a centimetre in length, and opening 
by a slit along one side (Figs. 4, 5). 
Conclusion. 
It is evident that Calobryum and Haplornitrium , although differing 
in certain particulars, e. g. the position of the archegonia, are closely 
related, and the establishment of a special family, Calobryaceae, to include 
these, is entirely warranted. The relationships of the Calobryaceae with the 
other Hepaticae are very obscure. Goebel regards them as members of 
a series developed quite independently of the other foliose Hepaticae. 
The development of leaves has evidently occurred in several quite 
independent series among the Liverworts, and the Calobryaceae probably 
represent the end of such a series, and are not closely related to the foliose 
1 Johnson, D. S. : The Development and Relationship of Monoclea. Bot Gazette, xxxviii. 
185-205, 1904. 
