Evans .— Vegetative Reproduction in Metzgeria. 291 
the postical surface. The hairs sometimes spread, but are more likely to 
be at right angles to the surface of the gemma. The convex antical surface 
is occasionally destitute of hairs, but usually bears a few near the centre, and 
these antical hairs are considerably longer than the marginal. 
The germination of a gemma was observed in a single instance. The 
marginal hairs had grown longer, and assumed the function of rhizoids, 
holding the gemma firmly to the surface of a leaf. The apical end of the 
gemma had grown out into a short thalloid structure which had produced 
a number of scattered postical hairs also acting as rhizoids. The majority 
of these hairs were situated close to the margin. Further differentiation 
of the thallus had also taken place, a rudimentary costa having made its 
appearance. It will be seen that the dorsiventrality of the gemma here 
persists in the young thallus, whereas in M. Liebmanniana it apparently 
disappears. 
Metzgeria disciformis, sp. nov. Pale green, more or less tinged with 
blue, growing in depressed mats : thallus prostrate, repeatedly dichotomous, 
well-developed branches about 1-2 mm. wide and from 1 to 2 mm. long 
between the forks, plane or slightly convex ; costa bounded antically by 
two rows of cortical cells and below by four rows (rarely only two or three); 
wings mostly from fifteen to twenty cells broad, the cells with slightly 
thickened walls, but without evident trigones, averaging about 25 x 21 /x, 
and not varying much in size in different parts of the thallus ; hairs 
restricted to the margin and to the postical surface of both wings and 
costa, sometimes few, but usually abundant along the costa, marginal hairs 
averaging about 90 /x in length, straight or nearly so, occurring singly, 
slightly displaced to the postical surface: inflorescence not seen: gemmae 
arising from the antical surface of the wings, in the form of circular concave 
disks, one cell thick throughout, abruptly contracted at the base into a 
short stalk composed of two or three cells, apical cell single, antical hairs 
few or wanting, borne near the centre of the convex surface, marginal hairs 
numerous, but much shorter, usually displaced to the postical surface. 
On leaves. New Zealand : without definite locality or date (Colenso, 
No. 1997). The specimens were communicated to the writer under the 
name M. australis , Steph., a species which is now considered a synonym of 
M. nitida , Mitt. They differ, however, very markedly from this species. 
Except for its small cells and peculiar colour the present species agrees 
pretty closely with M. furcata in its vegetative structure, the costa being 
built up according to the same plan, and the distribution of the hairs being 
much the same. The antical gemmae will at once serve to distinguish it. 
Their marked dorsiventrality is perhaps their most striking characteristic. 
It should also be noted that the antical surface of the thallus bears a few 
scattered hairs in rare instances, a condition which should doubtless be 
regarded as abnormal. 
U 2 
