4i5 
Lang . — On the Morphology of Cyathodium. 
this. Oil-bodies were absent from C. cavernarum. Their abundance in 
C. foetidissimum may perhaps be placed in relation to the aromatic scent 
of the plant when fresh. 
In median longitudinal sections of the vegetative apex in both species 
there appeared to be a single initial cell cutting off segments parallel to its 
base (Fig. 8). The details of segmentation as seen in surface view were 
followed in C. cavernarum (Fig. 27). There is a single rectangular initial 
cell present which cuts off segments parallel to its two sides and to its base. 
The shape of the initial and its segmentation differs when an apex is forming 
archegonia, and the basal tissue immediately behind it is more than one cell 
thick (cf. Figs. 10 and 34). 
Sexual Organs and Involucre. 
Both species were monoecious, the archegonia being formed in acropetal 
succession in relation to the apex of a branch of the thallus, while the 
antheridia are borne on small disk-shaped antheridiophores, developed from 
the lower surface of the thallus. In C. foetidissimum (Figs. 1, 9, 10) the 
antheridiophore springs from the midrib, and is situated a short distance 
behind the archegonial group or groups developed from the apex of the 
branch. In C. cavernarum (Figs. 25,#, 28) the antheridiophores are borne 
close to the margin of the thallus. The groups of archegonia are developed 
at the apices of branches of the thallus, and the antheridiophores very 
commonly alternate with them (Fig. 28). In other cases an antheridiophore 
may stand beside an archegonial group in the same apical depression, or it 
may be developed from the margin in no definite relation to the apex. 
In one case a young antheridiophore was seen arising from the margin 
of an older one. 
The antheridiophore of C. foetidissimum is attached by a short stalk 
to the midrib (Figs. 9, 10). It is transversely elongated, and the upper 
surface of the disciform summit is crowded with the projecting openings of 
the chambers in which the antheridia stand. In a longitudinal section 
passing through the stalk the latter is seen to expand slightly into the 
basal region, upon which a number of narrow chambers, each containing 
a single antheridium, are borne. The outside is formed by a single layer of 
cells continuous with the basal tissue ; this, unlike the septa between the 
antheridia, persists at maturity. The marginal cells of this peripheral layer 
project as a ridge circumscribing the upper face of the antheridiophore. 
The development of the antheridiophore in this species could not be 
followed in detail. A single specimen showed that it arose as a disk- 
shaped outgrowth from the lower surface, just behind the anterior margin, 
and was protected when young by large ventral scales. The two specimens 
that contained unopened antheridia showed that the youngest were situated 
at either end of the transversely extended disk. That a succession of 
