62 JAMES MURRAY 



will realise the desirability of collecting some moss for the sake of its fauna. The 

 moss-fauna of rotifers consists chiefly of Bdelloids, though there are a few others 

 which have adopted the same habitat. 



Origin of the Rotifer Fauna. In the present state of our knowledge it would 

 be premature to discuss the origin of the Antarctic Rotifer Fauna with any expecta- 

 tion of arriving at definite conclusions. We know almost nothing of the geological 

 history of Antarctica, especially of its recent glaciation ; we know nothing of the dis- 

 tribution of the Rotifera round the fringe of the continent (the heart we may infer to 

 be as dead as anything on earth) ; and our knowledge of the Rotifera of the nearest 

 land-masses and of the scattered islands of the southern hemisphere is inadequate. 



It may, however, be permitted to discuss in a tentative manner the bearing of 

 the known facts. It may safely be assumed that the Antarctic Region has known 

 periods of greater glaciation or of greater cold than at present, and periods of temperate 

 or warm climate. Is it possible that the rotifer fauna is aboriginal, and has survived 

 through the various climatic changes of long geological ages ? 



Judging from the summer condition of the Antarctic coast at present, it does not 

 seem too much to suppose that during the coldest periods there might always be 

 some rock faces so inclined as to make the most of the northern sun, and so form 

 little pools where the rotifers might live. The rotifers have been proven to survive a 

 lower temperature than any yet known under natural conditions on the earth, and 

 we have seen (under descriptions of Adineta grandis and Philodina gregaria) that 

 they do not ask for much in the way of luxury. Give them a week or two of warm 

 weather ( + 40 F. or so) and they are content to be frozen up for years. 



Periods of intense cold need not be periods of great precipitation, as we see in the 

 present low snowfall in South Victoria Land, and thus the bearing of temperature on 

 the problem falls to be separately discussed from that of glaciation. Has there ever 

 been a period when the glaciation was such that the very mountain peaks were covered 

 by a thick ice-cap which would scrape the rotifers, in common with all other living 

 things great or small, off the surface of the continent? That will not be discussed 

 here, but short of such a mechanical destruction as extreme glaciation or complete 

 submergence would achieve, I see no reason why there should not always have been 

 rotifers on the coast at least of the Antarctic continent. 



The peculiarities of the species of rotifers which at present appear to be peculiar 

 to the Antarctic are not very great, morphologically considered, yet they are great 

 enough to require us to presuppose a very long isolation if they have been acquired 

 in their present location. For four of them it would be difficult to suggest a probable 

 ancestor among known species. Although our list of fourteen species shows five new 

 and nine previously known, the amount of peculiarity is greater than these figures 

 would indicate. Three species indicated bjr marks of interrogation in the table 

 given differ more or less from their supposed types elsewhere. It was doubtful 

 whether they should be regarded as new species or as varieties. In such cases one has 



