324 



GeoTQC : Lincolnshire Freshwater Mites. 



promises to be exceptionally interesting-. Excursions in the 

 vicinity will be numerous, so that those who are not so fond of 

 garden parties, etc., will be able to occupy their time profitably. 

 The Friday evening discourse will be delivered by Dr. R. Munro 

 on ' Man as Artist and Sportsman in the Palaeolithic Period,' 

 and on Monday evening Dr. A. W. Rowe will discourse on 

 'The Old Chalk Sea, and Some of its Teachings.' 



LINCOLNSHIRE FRESHWATER MITES. 



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



Kirton-in-Lindsey, Lincolnshire. 



Arrhenurus compactus Piersig. This imcommon water 



mite very much resembles at 

 first sight, A. ornatus. It was 

 first described by Professor 

 Piersig in 1894 (^^^ Zool. 

 Anz., V. 17, p. 117). Its 

 colour is bluish-green, and the 

 back humps are considerably 

 separated from each other. The 

 obvious distinguishing mark 

 between this mite and A. 

 ornatus is the structure of the 

 petiole, which does not possess 

 the sharp - pointed, lateral 

 angles seen in the petiole of 

 ornatus, and is in consequence 

 more circular or club-shaped- 

 the central tooth, or bag-like 

 formation, is very prominent. 

 These parts are well shown in 

 Mr. Soar's figure, but are best 

 seen when the creature itself is 

 examined under the micro- 

 scope, either alive or in pre- 

 servative solution. Mr. Soar's 

 measurements are : — Leng^th, 

 0*96 mm.; breadth, o"72 mfh.; 

 length of petiole, o'i5 mm. 

 I have not heard of its being 

 recorded by any other observer in Great Britain. 



Nat iiralist. 



Arrhenurus compactus Piersig. 



Upper figure, Dorsal surface of Mite. 



Lower figure, Ventral surface of tail, 



more highly magnified. 



