The Philippine journal of science. [Vol. 67, no. 1]

88

The Philippine Journal of Science

1938

of wide range. I cannot now authenticate the statement in my
treatise on Trichomanes,70 that T. bipunctatum, a Crepidomanes,
is in New Zealand; it is common in southern Polynesia, and
thence in Madagascar. Besides these large genera, New Zealand
has Cardiomanes, altogether isolated, Polyphlebium, related to
Vandenboschia, and Apteropteris, probably derived from Sphaerocionium. Diploophyllum (with another name) may be added
to this list if one choose to recognize it as a genus.
Antarctic America is still richer in peculiar species and genera. With its outlying islands it has Serpyllopsis, which has
been referred to both Trichomanes and Hymenophyllum. Hymenoglossum is as isolated as Cardiomanes. Leptocionium
shares the characteristics of Meringium and Sphaerocioniumn.
There survive then at least six genera restricted to the far
South. Of the genera which either never were there or do not
survive there, only Didymoglossum and Microgonium are on
both sides of the Atlantic. Didymoglossum has a representative in Natal, which suggests Antarctic origin; it does not
reach Malaya and Polynesia. Microgonium is doubtfully in
America.
The genera which do not occur in the far South can be derived
from those which survive there, in each hemisphere, locally,
from the local representatives of the originally Antarctic genera, with the single possible exception of Abrodictyum, which
may be derived from Selenodesmium, but is more isolated than
any other tropical genus. With this single possible exception,
then, the entire family consists of genera surviving in the far
South, or of the descendants of these genera. The geographic
evidence is conclusive.
Evidence that Antarctica could have been the source of the
family still remains to be presented, since the Antarctic continent is not now a place where any fern survives. There is not
much palaeontological evidence on the subject, but two quotations
may suffice as to the general fact. In the Glaciology of Wright
and Priestly, a volume of the report of the British Antarctic
Expedition, it is stated in italics: "Glacial conditions have
been the exception and not the rule in Antarctica." 71 And "In
the upper Oligocene or lower Miocene, once more a temperate to subtropical flora holds sway over some portion of the
Antarctic Continent." 72 No approximately complete land con

70 Page 177.

7 (1922) 44.

72 Op. cit., 446.