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Show 1897.] ON THE NON-MARINE FAUNA OF SPITSBERGEN. 793 7. Contributions to the Non-Marine Fauna of Spitsbergen.- Part II. Beport on the Rotifera. By D A V I D B R Y C E .1 [Received June 10, 1897.] The material received for examination was contained in 13 tins, and when handed to m e had already been encased for some months, yet without much prejudice to the vitality of the various microorganisms hidden within it. It consisted of Mosses, apparently of such species as usually grow in wet places (for species see ante, p. 785), and was still abundantly moist. In many cases, however, the moss-plants were so encumbered with soil and decayed fragments of preceding generations as to render their examination for the purpose in view an exceedingly difficult and a lengthy matter. Bepeated attempts were made to ascertain the presence of Boti-fera in the contents of each tin, with the result that 5 tins were found to contain from 4 to 15 species each, 2 tins one or two individuals only, and 6 tins none at all. In every case the dirt-laden material was quite unproductive, and some of the cleaner mosses were equally disappointing, whilst in none were the individuals more than moderately numerous. As was to be expected from mosses, the Bdelloid Botifera were by far the most numerous, both as to number of species represented and as to number of individuals seen. Among the Bdelloida, again, the genus Callldina was prominent, claiming no less than 13 of the whole 26 species on the list. But besides these 13 species, which were capable of recognition, 1 found various isolated examples which I could not with any satisfaction refer to any species described or even known to me, and it is likely that if examples had been more numerous I should have been justified in giving specific names to these forms. All the 26 species have been already met with either in England or in Germany, and it would seem that, so far as regards the actual species of moss-dwelling Botifera, there is little to distinguish the fauna of Spitsbergen from that of these countries. The interest of the list is, however, less in the number of species enumerated than in the evidence afforded of the vitality and endurance of these minute yet highly organized animals under such exceedingly trying conditions of life as those obtaining on the island of Spitsbergen. For under the most favourable conditions none of these creatures can have there a continuously active existence of more than three months. In more temperate countries the moss-dwelling Botifera are called upon to endure recurring periods of temporary drought, but such periods occur rarely except in summer, and are even then mitigated by nightly dews or occasional rainfall. For the greater part of the year, autumn, winter and spring, there is moisture sufficient for their wants, and, so long as the temperature does not fall below freezing-point, life goes on merrily and generation succeeds generation, whilst periods 1 Communicated by Dr. J. W. GREGORY, F.Z.S. |
