3. “Die tertiare Flora der Seymour-Insel,”
The Swedish Antarctic Expedition, as is well known, made the extremely important discovery of fossils in a sandstone formation of Tertiary age on Seymour Island (about lat. 64o S.), the present vegetation of which desolate spot is, according to Skottsberg, of the scantiest character, consisting of “faint traces of moss-tufts in rock crevices and two kinds of lichen with their body reduced to almost nothing more than the apothecia.” That the climate in Tertiary times was very different, and probably similar to that of the North Island of New Zealand to-day, is plainly evident from the identification of the fossils as follows:—
Miconiiphyllum australe, Dus., n.sp. (Melanostomaceæ), is related to the living Miconia species of south Brazil.
Lauriphyllum Nordenskjoldii, Dus., n.sp., is of doubtful affinity, but probably related to the Lauraceæ of subtropical South America.
Calcluvia mirabilis, Dus., n.sp. (Cunoniaceæ), is closely related to the south Chilian C. paniculata, D. Don, a forest-tree.
Laurelia insularis, Dus., n.sp. (Monimiaceæ), calls to mind the south Chilian tree L. sempervirens (Ruiz and Par), Tul., the genus consisting only of two or, according to some botanists, three species, one of which is endemic in New Zealand.
Mollinedia seymourensis, Dus., n.sp. (Monimiaceæ), is related to M. micrantha, Perk., a forest-shrub of south Brazil. The genus is confined to the tropics of South America, and especially of Brazil.
Drimys antarctica, Dus., n.sp. (Magnoliaceæ), is closely related to D. Winteri, Forst., a very common low tree or shrub of Chile and Fuegia. The genus consists of about twelve species occurring in South America, New Zealand (three endemic species), Australia, New Caledonia, New Guinea, and Borneo.
Two species of Iliciphyllum related to the south Brazilian Ilex species (Ilicinaceæ): Lomatia angustiloba, Dus., n.sp.; L. Seymourensis, Dus., n.sp. (Proteaceæ), are closely related to the south Chilian-Patagonian species of the genus. Lomatia occurs in South America, Australia, New Caledonia, Polynesia, and China, but is wanting in New Zealand.
Knightia Andreæ, Dus., n.sp. (Proteaceæ), is of especial New Zealand interest, since the genus contains only three species; one, the type, being confined to New Zealand, and the other two endemic in New Caledonia, but belonging to a subgenus Eucarpha.
Fagus Dicksoni, Dus.; F. obscura, Dus., n.sp. (Fagaceæ), have no living representatives in the Southern Hemisphere, but the former is probably identical with a fossil Fuegian species.
Nothofagus magellanica, Englh.; N. pulchra, Dus., n.sp. (Fagaceæ): The former is probably identical with a fossil species on Fuegia, and the latter is related to the present temperate South American species. The genus is confined to temperate South America, New Zealand, Australia.
Myrica Nordenskjoldii, Dus., n.sp. (Myricaceæ), is related to fossil species in the Tertiary rocks of South Chile.
Araucaria imponens, Dus., n.sp. (Pinaceæ-Araucariæ), is an extremely important discovery, since it is not closely related, so far as habit goes, to the well-known Chilian A. imbricata, but resembles much more the far-distant A. braziliensis, of Brazil, and A. Bidwillii, of Australia. It is interesting to point out that Dusen some time ago proved the existence of a fossil Araucaria in Fuegia.
Nine species of ferns are noted, amongst which are Alsophila antarctica, related to the south Brazilian A. feeana, and Polypodium Nathorstii, Dus., n.sp.; Pæniopteris blechnoides, Dus., n.sp.; Asplenium antarcticum, Dus., n.sp.; Dryopteris Seymourensis, Dus., n.sp.; D. antarctica, Dus., n.sp., all of which more resemble subtropical forms of south Brazil than those of temperate South America.
The remaining fragments of leaf-impressions were not in sufficiently good preservation to allow of their determination with any degree of certainty.
A superficial glance over the above determinations of the specimens shows that the former plant-world of Seymour Island is related to two present South American floral regions—namely, the temperate flora of southern Chile, and, but even more closely, the subtropical plant-world of south Brazil. Thus the Tertiary flora of Seymour Island is a mixture of temperate and subtropical species. Dusen seeks to explain this remarkable phenomenon. He dismisses the idea of transportation by ocean-currents, as such would bring a dispersion rather than a collecting-together of plant-remains: his opinion is that there existed in Tertiary times on Seymour Island a mixed flora, partly temperate and partly subtropical, the former occupying the high lands and the latter at low levels, such as is the case in southern Chile at the present time, and that the remains of both now exist together, the temperate species having been brought to the lowlands by streams and there mixed with the remains of both of the subtropical forms. [The reviewer is of opinion that probably temperate and subtropical forms grew side by side, as in almost any lowland forest of New Zealand at the present time, and that the hypothesis of floods bringing down the mountain-plants is not required.]
That the plant fossils of Seymour Island probably belong to the Tertiary period is supported by the fact that they are very similar to existing species.
The author lays stress on the fact that there is little relationship between the flora under consideration and that of Australia and New Zealand as now existing. He cites Knightia as the sole connecting-link, and concludes that land connection between the Antarctic and Australasia must have been severed at a very early date—namely, before Tertiary times. The species of Knightia is considered by the author, together with that of New Zealand, to have been derived from the same antarctic stem-forms.
[The above summary of a work of the greatest scientific importance to us in New Zealand is unfortunately only built up from two reviews—one by Neger, in Naturwissenschaftliche Wochenschrift for the 5th July, 1908, and the other by Gothan, in Botanisches Centralblatt of the 12th January, 1909. The reviewer considers that too little stress is laid on the Australasian affinity with the Tertiary flora of Seymour Island when, besides the presence of Knightia Andreæ, whose only close relative is K. excelsa, of New Zealand, there are also such remarkable genera, common to New Zealand and Australia as well as South America, as Nothofagus, Drimys, and, above all, Laurelia. Australian affinity is also shown by Lomatia and Araucaria, though this latter might suggest an earlier land connection than Tertiary.]