94 The Irish Naturalist. [April, 



A NKW WATER MITE FROM UI.STKR. 



BY J. N. HALBKRT. 

 [Read before the Dublin Naturalists' Field Club, March 13th, 1900. J 



During the summer and autumn of lastj^ear Mr. W. F. de V. 

 Kane very kindl}- sent to the Museum several small collections 

 of water mites, captured while dredging for Kntomostraca in 

 various localities in the North of Ireland. One of these 

 gatherings, made towards the end of September in Upper 

 lyough Erne, contained several rarities, among the rest a 

 most interesting Arrcnujms, in structure quite unlike any of 

 the previously-known British species. This specimen was 

 subsequent!}' lost. About a month later Mr. Kane ver}^ 

 fortunately succeeded in capturing both sexes of what is 

 without doubt the same species in a lake in the County of 

 Monaghan, and from these specimens the following notes have 

 been made. 



The newly-discovered mite is of considerable interest, as 

 the only known lorm at all resembling it in structure is a 

 Swedish species, Arrenuriis 7iobilis, described by Neuman^ in 

 1880. 



Acarefulcomparisonof the Irish mite with the description and 

 figures of A. nobilis shows that, although they are evidently 

 closely allied forms, the}^ cannot be united under the one specific 

 name, and in this opinion I am supported by Dr. R. Piersig, 

 of Annaberg, to whom drawings have been submitted. It may 

 be worth noting that Neuman's species has apparently not 

 been detected b}^ recent workers, and no trace of his unique 

 example is now to be found amongst the remnants of his 

 collection preserved in the Gotenburg Museum. ^ 



The species oi Arre7i2crus are amongst the most beautiful of 

 the HydraduiidcB. They are remarkable for the hard skin, 

 which is always more or less coarsely granulated, and the 

 great specialization in structure attained by the males. The 

 species are comparatively numerous, and are as a rule very 

 brightly coloured. The species has been named after its dis- 

 coverer, who has been instrumental in bringing to light many 

 rare forms from our northern lakes 



^ " Om Sveriges Hydrachnider," Kongl. Svcnsk. Vet. Akad. Hand!., xvii., 

 No. 3. 



^ Zoolog. Anzeigcr^ xx., 1897, p. 333. 



