242 THE AMERICAN MONTHLY [Aug 



about it than that it is a member of the acarina. I have 

 often ask microscopists when they have been collecting to 

 kindly save me any water mites they might find of a par- 

 ticular genus, but they invariably answer "I only know 

 the common red one," and are very much surprised when 

 they are told that there are between twenty and thirty 

 distinct species of red mites found in fresh water in 

 England. 



In England we know of twenty-six distinct genera, and 

 seventy-two identified species, only two of which have 

 been named by Englishmen — Thyas petrophilus (Michael) 

 and Arrenurus novus (George). The red mites which I 

 kuow, are distributed as follows: Arrenurus three, Piona 

 one, Nessea five, Limnesia, three, Hydrachna two,Hydro- 

 droma two, Marica one, Diplodontus one, Eylais one, 

 Bradybates one, Limnochares one, Thyas two. This list 

 will no doubt be added to later on. I only wish in this 

 paper to mention a very few of the red mites, chiefly to 

 show the difference in the external structure of these 

 beautiful creatures. To mention and figure all the known 

 British red mites would take up too much space. 



Water mites, as far as is known, generally deposit 

 their eggs on the leaves and stems of water plants-. The 

 under side of the leaf of Anacharis often shows how the 

 ova of a beautiful red mite with blue legs — Limnesia 

 histronica (Hermann) — are deposited. The eggs are not 

 red, but deep orange-yellow. After a number of days, 

 the time varying in different species, the larva, which is 

 hexapod, is hatched out. During this stage many if not 

 all larvae become parasitic on some other form of pond 

 life A small red mite in the larval or parasitic stage, 

 can' be taken from the leg of a water-boatman Corixa 

 Greoffroyi ; it is very small, and one recently found had 

 not taken up its abode very long, because the legs were 

 still visible. When they have lived on their host for 

 sometime and have grown very considerably, the legs havo 



