Q 



59 



NOTES AND OBSERVATIONS ON THE LIFE-HISTORY 



OF FRESH-WATER MITES. 



By C. D. Soar, F.RM.S. 



{Read March hVh, 1906.) 



Plates 26—30. 



It was nearly ten years ago that I first made a few remarks on 

 the Hydrachnidae before this Club and mentioned some facts 

 from my own observations on their early stages. Although some 

 of my present remarks will be new, I shall recapitulate part 

 of what I previously said, with this difference, that I am now 

 able to illustrate the points which I wish to bring to your notice. 

 There are at present more than sixty known genera of water- 

 mites, and I do not think that in the case of more than about six 

 of these have we any really definite information upon their early 

 stages. Beyond the interest attached to the subject itself, I am 

 also hoping to induce some of our members to note and report any 

 little piece of evidence that may turn up during their own collect- 

 ing expeditions, so as to help in adding links to the chain of the 

 life-history of these interesting little creatures. 



Some of the conclusions arrived at, and deductions drawn, may 

 have to be modified as more facts become known. But when thi y 

 are known I have no doubt but that we shall still find that a number 

 of the habits of|these little creatures are due to their environment, 

 and the particular conditions under which they happen to be 

 living at the time and place of capture. 



The life-history of water-mites can be conveniently divided into 

 four distinct stages — the egg, larva, nymph, and adult— and 

 these we will take in; their proper order. 



As far as we know at present, all the Hydrachnids deposit eggs. 

 None bring forth their young alive. But they do not all deposit 

 their eggs in the same manner. Some fix them with a gelatinous 

 film to some convenient object; some lay them inside the shell- 



Jourx. Q. M. C, Series II.— No. 59. 26 



