344 



George: Lincolnshire Freshwater Mites. 



granules, vacuoles, foam structures, fibrils, etc., can be produced 

 as secondary structures by its own activity. 



The structure and function of other cell organs are dealt 

 with, including the chlorophyll corpuscles, eye-spots, starch- 

 formers, centrosomes, etc., and among other interesting topics 

 discussed are experimental observations on the activities of the 

 nucleus, the differentiation of structure visible in the living cell, 

 the cell-structure of the blue-green algaj and bacteria, the 

 function of the nucleus in the blue-green algae, and some 

 observations on the evolution of the nucleus. 



LINCOLNSHIRE FRESHWATER MITES. 



C. F. GEORGE, M.R.C.S. 



Arrhenurus truncatellus Miiller. This mite belongs to 

 Sig. Thor's division Truncaturus. It was first described by 

 Miiller in his work on ' Danish Freshwater Mites,' published in 

 1 781, under the name of Hydrachna truncatella. He also gives 



Figs. I and 1,— Arrhenurus truncatellus truncatellus Muller— Piersig. 



a coloured figure, 'Tab. VII., Fig. 6.' It does not appear to 

 be very common in Lincolnshire, as I found a single specimen 

 in ]\Iay of the present year. It will be remembered, perhaps, 

 that in my list of Water Mites, published in 'The Naturalist' 

 for August 1900, I mention Arrhemirus truncatellus, and refer 

 to a figure of it in 'Science Gossip' for April 1884, page 210. 

 The mite there figured and described, however, is not the mite 

 described by Miiller, as Dr. Piersig pointed out to me, but 

 differs chiefly in having two convex bladder-like projections at 



Naturalist, 



