Abstract
LONDON Linnean Society, March 17.—Mr. Carruthers exhibited a section of a fossil Osmunda from the eocene beds of Herne Bay, in which not only the forms of the cells were preserved, but the contents of the cells, and even the Starch-granules. Before its conservation it had been attacked by a parasitic fungus, the mycelium of which is preserved, in precisely the same condition as it would be in a recent specimen.—Dr. Hooker read a further communication from Sir Henry Barkly on the Flora and Fauna of Round Island. The highest point of the island is 1,049 feet above the level of the sea; the summit is smooth, with three large and remarkable blocks of granite. It is entirely composed of tufa, mixed with volcanic sand in perfectly preserved strata. The deeper ravines are crowded with Jofty palms. Of the twenty-six flowering plants gathered, the greater number belong to the orders Graminece, Pandanacece, Palmacece, Ebeitacecc, Cinchonacece, Composites, and Asclepiadece. The proportion of Endogens to Exogens is very large, namely, twelve to fourteen; but this proportion by no means represents the enormous preponderance of the former in individuals, probably amounting to 99 per cent. Some of the Exogens are specifically identical with those of the Mauritius, but few of the Endogens; those of the former class which are common to the two islands have probably been introduced at some remote period. Of the three cryptogamic plants observed, one was a moss, probably a Sphagnutn, one a Selaginella, certainly a new species, and one a widelyspread fern, Adiantum caudatum. Of the five grasses the most abundant is identical with the Indian Lemon-grass. The Cyperacece are represented by one species, Scirpus maritimus. The Pandanacece are very remarkable; Pandanus titilis occurs, but in one spot only, rare, and no doubt introduced, whilst the other, an allied species (P. Vandermeerckii, is quite peculiar to the islet). Of Palms there are no less than three species, probably all peculiar, the most remarkable being the bottle-stemmed species (a Hyophorbe) already described as peculiar to the island. The only other Endogen belongs to the order Liliaceæ, and is an aloe, growing on the summit, and probably a new species. Of Ebenaceæ there are three species, and two Asclepiads with trailing stems; one species of Myrsineæ, new; two Compositæ, one of them a Sonckus, both probably introduced; one species of Combretacece and one of Myrtaceæ; two Cinchoneæ, and a small tree about twelve feet high, resembling the Blackwellia of Mauritius. It will be seen that while the genera of the Round Island Flora are Mauritian, the species are mostly peculiar. It is probable that the whole group of islands—Mauritius, Boilrbon, Round Island, He de Serpents, Rodriguez, with the smaller islets, and probably Madagascar—are fragments of a vast continent. As regards the Fauna, there are no indigenous mammalia, although goats and rabbits have been introduced and have multiplied exceedingly, and no land birds, not even the Mauritian pigeons. The island seems, on the other hand—perhaps from the absence of mammalia and birds—very favourable to reptile life. Of Chelonians, a female land-tortoise had previously been captured on the island. Four distinct Saurians were found, the largest exceeding a foot in length, a native of Madagascar, but not of Mauritius or Bourbon; one species, at least is altogether new. The four Ophidians are all undesenbed, no authentic evidence being known of any such having at any time been indigenous to the Mauritius group. No Batrachians were discovered, and the time was too short to collect the Fish which abounded in the freshwater pools. Only one Gasteropod was collected, probably Cyclostoma hemistoma. Of Arachnida, the spiders are numerous and interesting, of four kinds, belonging to as many different families, two common to Mauritius and two not; also three scorpions, one measuring five inches, none of them Mauritian. Only one Myriapod was captured, a centipede six inches in length, belonging to India, but found also in Rodriguez. There were six Coleoptera, none of them Mauritian, though not very dissimilar. Of Orthoptera, one Plasma, peculiar to the island, and a grasshopper, also thought to be new. The Neuroptera included only one specimen of a dragon fly, and the Hymenoptera only a single bee. Generally speaking, the Fauna was of the type of the Malayan archipelago, with greater resemblance to that of Madagascar than of Mauritius or Bourbon. The reptiles have been sent to Mr. Gunther of the British Museum for examination and description, and specimens of the plants to the Kew Herbarium. Thus it will be seen that this little islet, not a mile in diameter, and only thirteen distant from the great island of Mauritius, is unique in respect of the peculiarity of both its animal and vegetable productions. In the matter of Ophidians it is especially so; the absence of them in other oceanic islets throughout the globe being one of the most remarkable features of their history.
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Societies and Academies . Nature 1, 567–570 (1870). https://doi.org/10.1038/001567a0
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DOI: https://doi.org/10.1038/001567a0