306 DAVID BRYCE ON 



time the well-known investigator of Scottish Rotifera. His 

 report on the collection (5) was submitted to the Royal Physical 

 Society of Edinburgh in the autumn of 1907. The Rotifera 

 obtained from the Spitsbergen moss were dealt with separately, 

 though at no great length. I find that of the 19 forms, which 

 he observed, only 5 had been previously recorded by me, and one 

 by Richard, and 13 species were accordingly additions to the 

 Spitsbergen list. 



In 1918 Olofsson published (8) an account of researches 

 carried out in the summer of 1910, on the Crustacea and 

 Rotifera observed and collected by himself in numerous lagoons 

 and ponds throughout Spitsbergen and the various islands 

 in the vicinity. All the Rotifera found by him belong to the 

 order Ploima, and make a considerable contribution to the list 

 of that group, which was only poorly represented in the 

 mosses examined by Murray and myself. Altogether Olofsson 

 enumerates 34 species or well-marked varieties, including several 

 described as new to science. Of the 34 forms 3 had been already 

 seen by Richard, 2 by Murray, and 2 by myself. 



In the mosses now reported on I have found 28 species or 

 well-marked varieties. Of these 18 had previously been re- 

 corded ; and 10 species remain as new records, bringing the 

 total up to 81 species or well-marked varieties. 



In considering the results of the three series of moss-gatherings, 

 one cannot help remarking that in each the Bdelloid Rotifera have 

 greatly preponderated, in the number of species obtained, over 

 the Ploiima and Flosculariaceae. In the combined total of 51 

 species and varieties obtained from mosses, there are 35 Bdel- 

 loida, 15 Plomia, and 1 Floscularian. This apparent dispropor- 

 tion is due to the fact that most of the Bdelloida are habitually 

 moss-dwelling and are rarely or never found in pools or other 

 waters. If collections had been made in the ordinary way from 

 available pools or lagoons, the proportions of these groups 

 would probably have been more than reversed, as has in fact 

 been shown by Olofsson's results. It is not so much a question 

 of temperature as of the customary habitat of the species. Where 

 moss gatherings were made, it resulted that the Rotifera found 

 were principally Bdelloida. A few species of Ploima are also 

 generally found in mosses. Apart from one Ploimid which is 

 not known to have been hitherto found in Europe, I find that 



