227 
Inter-Relationships of the Anacrogynce. 
the leaves themselves are in these species inconspicuous (except at 
the growing-point) owing to their early loss of individuality, of the 
eighteen Anacrogynous genera here dealt with, no less than eight 
are distinctly foliose. The vegetative organisation of these genera 
( Noteroclada, Blasia, Cavicularia, Fossombronia, Petalophyllum , 
Treubia, Haplomitrium, and Calobvyum) has already been described 
in some detail. 
The Calobryaceaa stand well apart from the other Anacrogynae, 
but the three remaining families are connected by cross-affinities, 
besides showing parallel developments in the position, investment, 
and structure of the sexual organs and sporogonia, as well as in the 
vegetative organs. The Aneuraceae and Blyttiaceae have elongated 
capsules (except Metzgeria), with a more or less highly developed 
apical elaterophore. Only in Aneura and Metzgeria is this structure 
an efficient mechanism for active spore-dispersal, for in these genera 
alone does the capsule-wall regularly split into four valves, each 
bearing at its tip a quarter of the split-up elaterophore; in the 
other genera the capsule dehisces by a varying number of valves 
which usually remain coherent at the tip. In all the genera placed 
in these two orders, with the exception of Aneura and Metzgeria, 
the fibrous thickenings in the capsule-wall are either absent or 
feebly developed, while the elaterophore is represented by a flattened 
cap of cells with some elater-like outgrowths hanging down into the 
cavity of the capsule. Apart from the restriction of the sexual 
organs to special short branches (lateral in Aneura, ventral in the 
other three genera) there is no constant character separating the 
Aneuraceae from the Blyttiaceae. As regards the investment of the 
sporogonium, two genera in each family have no well-developed 
envelopes outside the calyptra, which is massive and fleshy ( Aneura, 
Metzgeria, Symphyogyna, Makinoa). A tubular envelope (“ perianth ”) 
is present in Podomitrium. Umbraculum, Blyttia, and Morckia, 
surrounding the archegonial group and arising either before or after 
fertilisation of one of the archegonia; in these four genera there is 
an additional investment (“involucre”) outside the perianth, 
consisting of a single scale ( Umbraculum ) or of a cupule-like circle 
of scales. In Symphyogyna and Makinoa, there is also a single 
involucral scale, as in Umbraculum’, in Aneura and Metzgeria, the 
archegonia are protected by the incurved edges of the short female 
branch, and the young sporogonium by the thick calyptra. Little 
can be inferred from these different arrangements, beyond the 
generalisation that while a short collar-like outgrowth, or a circle of 
