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Britlab Ibpbracbnib^, 



Part II. By Charles D. Soar, Plate XV. 



^"^HE next genus we have to notice is the well-known Arre7iii 

 rus. I say well known, because this genus was described in 

 extenso in a series of articles which appeared in Science 

 Gossip some years ago, written by Mr. C. F. George, of Kirton 

 Lindsey. The genus Arrenurus contains mites of the most 

 beautiful shapes and colours, the colours being especially brilliant, 

 some of them appearing quite metallic, and look most gorgeous 

 when viewed under reflected light. In shape the males are as 

 different from the females as it is possible to imagine. This genus, 

 when thoroughly worked out, will, I have no doubt, be found to 

 be the most prolific in species of all the British Hydrachnidae. A 

 great many species are very common. No collector or lover of 

 pond-life but has at some time or other taken some of these 

 interesting and prettily coloured mites home in his bottle, perhaps 

 admired them, and put them on one side and thought no more 

 about them ; very few naturalists have thought it worth while to 

 write about them. 



If the reader who is interested in this genus will turn to Science 

 Gossip for the years 1881 to 1884 (Vols. XVIL— XX.), he will 

 find several papers devoted to this family by Mr. C. F. George, 

 who described and figured about sixteen of the species found in 

 the British Isles. My intention, however, in this paper is to speak 

 of the genus and give its characteristics, so that anyone will know 

 an Arrenurus when they find one. The number of known British 

 species I hope to give later on. 



Genus Arrenurus (Duges). 

 (A. Duges, Recherches sur I'ordre des Acariens, etc., Ann, des 

 Sciences Nat.,, Tom. I., p. 17, 1834.) 

 Body chitinous, with a maculated appearance in both sexes. 

 On the dorsal side is a depressed line, which is oval in shape in 

 the female and of a horse-shoe shape in the male. The legs are 

 strong and well supplied with swimming bristles. All the tarsi 

 have claws. Mandibles in two distinct portions. Eyes widely 

 separated and near margin of body. On each side of the opercu- 

 lum are numerous copulative pores set in a special plate. Palpi 

 short, the fourth joint longer and stronger, the fifth joint forming 



