1897.] ON THE NON-MABINE FATJNA OF SPITSBEEGEN. 793 



7. Contributions to the Non-Marine Fauna of Spitsbergen. — 

 Part II. Report on the Rotifera. By David Bryce.' 



[Eeceived June 10, 1897.] 



The material received for examination was contained in 13 tins, 

 and when handed to me had already been encased for some months, 

 yet without much prejudice to the vitality of the various micro- 

 organisms 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 frag- 

 ments of preceding generations as to render their examination for 

 the purpose in view an exceedingly difficult and a lengthy matter. 

 Repeated attempts were made to ascertain the presence of Roti- 

 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 indi- 

 viduals more than moderately numerous. 



As was to be expected from mosses, the Bdelloid Rotifera were 

 by far the most numerous, both as to number of species repre- 

 sented and as to number of indi\iduals seen. Among the 

 Bdelloida, again, the genus CaUidhm was prominent, claiming no 

 less than 1.3 of the whole 26 species on the list. But besides these 

 13 species, which were capable of recognition, I 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. AH 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 Rotifera, 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 Spitsbei'gen. For under the most favourable conditions 

 none of these creatures can have there a continuously active 

 existence of more tlian three months. In more temperate countries 

 the moss-dwelling Rotifera 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. Ror 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 



^ Communicated by Dr. J. W. GKEGORy, F.Z.S. 



