WATER .MITES 57 



WATER MITES. 



By William Williamson, F.R.S.E. 



One is inclined to think that in many cases the lack of 

 interest in Natural History is not due so much to indifference 

 on the part of the individual as to lack of knowledge of what 

 to seek out and how to seek it. Many books throw so little 

 light on the different groups of creatures, that darkness is 

 only made more evident. Specialisation has become intense, 

 and the general writer, in his endeavour to cover much 

 ground, must leave many things unsaid, with the result that 

 the reader's acquired ideas are of a nebulous type. The 

 solution of the difficulty lies in the hands of the specialist a 

 fact which was recognised by German zoologists in that 

 useful series of handbooks, Susswasserfauna Deutschlands, 

 in which the characteristics of various groups are set forth 

 clearly and the identification of miscellaneous material 

 greatly simplified to the collector. The publication of 

 a series of similar manuals for Britain is not at present 

 feasible ; however, a step in the right direction would be 

 made if specialists were to supplement the studies which 

 have already appeared ("Study of the Diptera," ante, 1916, 

 p. 85, and "Scottish Hairworms," ante, 191 5, p. 1 11, 136, 142) by 

 studies of the less known groups, and it is believed that 

 by the dissemination of this knowledge much good material 

 might be salved for the benefit of zoology. 



In consonance with the foregoing observations, a study 

 of the water mites is submitted, in the hope that others may 

 be attracted to the subject. 



General Characters. 



Before going further, reference may be made to certain 

 structural details. An inspection of each of the species 

 referred to below will show that there are eight legs four 

 on each side and that these articulate with four groups of 

 plates two on each side of the antero-ventral body surface. 



