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Mr Warburton, The Geographical Distribution 
The Geographical Distribution of the Acarine Family Oribatidae. 
By C. Warburton, M.A., Christ’s College. 
[Read 4 May 1908.] 
The Oribatidae are minute free-living Acarines, rarely attaining 
a millimetre in length, and inhabiting moss and vegetable debris, 
or living on or under the bark of trees. They are vegetable 
feeders, not eating the moss or the bark itself, but apparently 
browsing on the microscopic fungoid growths they find in such 
situations. They also eat pollen. 
Very few naturalists have devoted attention to this group and 
their investigations have practically been limited to the places 
they themselves have visited, for the creatures are too small to 
attract the attention of the general collector and are only obtained 
in any numbers if deliberately searched for. Mr A. I). Michael 
was the first in this country to take up the study seriously ; a few 
Continental Arachnologists have investigated the Oribatid fauna of 
their own countries, and one or two American naturalists have 
described several species without, apparently, paying much 
attention to previously described European forms. Only in certain 
restricted regions, therefore, and in them by no means exhaustively, 
have the Oribatidae been hitherto investigated. 
Eighteen months ago, in a paper communicated to this Society 
by Mr N. D. F. Pearce and the present writer, attention was called 
to the fact that it was possible to transport moss or other material 
in hermetically sealed tins from very distant localities without 
injury to any living Oribatidae it might contain, if only the 
material were not in too dry a condition when collected, so that if 
anyone could be induced to undertake the small amount of trouble 
involved in gathering and transmitting moss from suitable localities 
the examination of its contents might be postponed till its arrival 
in England. Our eventual knowledge of Oribatid distribution 
seemed likely, by this means, to become very extensive indeed. 
Now 7 there appeared to me reasons for anticipating that the 
Oribatid fauna of widely separated localities would be highly 
characteristic, and that this group was extremely well adapted for 
affording indications of the correctness or otherwise of the accepted 
zoological regions. In the first place, whether or not the Acarina 
be a primitive group, it is impossible to consider the Oribatidae a 
primitive family of the Acarina. On the contrary they appear to 
be among the most highly differentiated of the mites. Again, 
they do not appear to possess any of the facilities for extensive 
distribution exhibited by certain other Arachnid groups. They 
