202 
F. Cavers. 
like the male branches. In Podomitrium the female branch is short 
but differentiated into a cylindrical portion which hears a narrow 
wing ; on the expanded end of the branch are developed the arche- 
gonia, surrounded by a collar-like envelope (involucre) with fringed 
margins (Fig. 30, I.) In Umbraculnm the wing of the female branch 
is more fully developed, and the involucre is reduced to a scale 
instead of forming a bell-like sheath (Fig. 31, III.) In Aneurn and 
Metzgeria, the sporogonium is protected until ripe by the calyptra, 
which is a thick fleshy structure, often hearing on its surface the 
unfertilised archegonia. In Podomitrium and Umbraculnm there 
arises within the involucre a second sheath (perianth) surrounding 
the archegonia ; in the former genus the perianth is laid down 
before fertilisation occurs, in the form of a few scales arranged in a 
ring, the scales being later carried up by active growth of the tissue 
at their base (Fig. 30, IV., V.), but in Umbraculnm the perianth 
arises after fertilisation in the form of a ring-like outgrowth of the 
tissue surrounding the archegonia (Fig. 31, IV.) 
In all four genera, the sporogonium has a well-developed seta 
which rapidly elongates when the capsule is mature and thrusts the 
latter through the calyptra, the capsule then opening, typically, by 
four valves extending from apex to base. The early stages in the 
embryogeny have only been studied in Aneura , and the following 
account is based upon the writer’s examination of the sporogonia of 
A. pinguis and A. latifrons. The lower (hypobasal) cell formed by 
the first transverse division of the oospore either undergoes no 
further development or divides by a few walls, chiefly transverse, to 
form a short appendage; hence practically the whole sporogonium 
(capsule, seta, foot) is formed from the upper (epibasal) half of the 
segmented oospore, the foot arising as a club-like swelling of the 
lower end of the seta. The epibasal cell first divides, as a rule, by 
a transverse wall, which separates the capsule from the seta. Then 
intersecting vertical divisions set in, together with further transverse 
divisions in both the upper and lower epibasal cells, so that there 
are now several superposed tiers consisting each of four cells. Up 
to this point, Aneura follows what is probably, with slight differences 
in detail, the development characteristic of all the Jungermanniales. 
In Aneura, as in other Anacrogynae which have been investigated, 
the capsule is derived from the uppermost tier of four cells, but in 
many Acrogynae one or more of the tiers formed in the lower epi¬ 
basal series may contribute to the formation of the capsule besides 
forming the seta. In both the capsule- and the seta-forming tiers, 
