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Show 794 MR. D. BRYCE ON THE [June 15, of cold, when the moss is frost-bound, are rarely of long duration. In the far north latitude of Spitsbergen, circa 78°, the frozen state is the rule, the moist the brief exception, and an individual Callidlna (whose average existence may be reckoned as comprising at least some three months of active life) may quite possibly live during several summers, expending its three months in annual instalments. This capacity for the endurance of long periods of cold was already known from Ehrenberg's (4) discovery of certain forms on the Swiss Alps at a great elevation. The few species noted by him all belong to the Bdelloida, so that whilst the present list widens the record as regards that group, it extends it to at least 7 species of the PloVma. _ There appear to be but two previous records of Botifera at so high a latitude. In 1862 A. von Goes recorded two species of Callidlna, which he had found in some moss ; the species were not, however, determined (" O m Tardigrader, Anguillulae m.m. fran Spetsbergen " Ofvers. K. Vet.-Akad. Forh. 1862, p. 18). In 1869 Ehrenberg (5) had brought to him some material which had been collected iii Spitsbergen in 1867. This material included some mosses, and in these he found one Botifer, Callidlna alplum, and an " egg of a Botifer " unknown, among several forms belonging to other orders. This statement occurs in a Beport upon the results afforded bv material collected bv the Second German North Bolar Expedition of 1869 and 1870*. For the rather lower latitudes of Greenland, several lists have already been published, the most important being contained in the treatise by Bergendal (1), in which are enumerated and discussed some 82 species collected by the author at various localities between the parallels of 66° and 70° N . during the summer of 1890. At first sight it appears curious that, with but three exceptions, none of the forms found by him in Greenland have occurred in the Spitsbergen material. Bergendal, however, devoted his attention chiefly to the ordinary water-dwelling Botifera, and seems to have rarely examined mosses. Nor does he seem to have been cognisant of the fact that moss-dwelling Botifera can be secured and studied at leisure months after collection, as was done by Ehrenberg and as has been done in the present case. There is therefore no real ground for comparison between his list and that hereto appended. It may be mentioned that, of the eleven species of the Bdelloida included by him, one only has been found in the course of this investigation. Notwithstanding their Arctic nativity, many of the species were kept alive for weeks in small cells, whilst others seem at this date (April 1897) to have permanently established themselves in a jar of water, into which I have from time to time thrown moss which I had washed, as well as washings after final examination. The majority of the species have already been sufficiently described, and in these cases I have merely indicated their comparative abundance in the five tins which yielded positive results. |