1 9 o 6- 1 9 o 7 . ] British Hydrachnidce : The Genus Fiona. 3 8 1 



The tarsus of third leg is very like that of both P. obturbans 

 and P. rotundoides. The distal end of patella has three long 

 swimming-hairs. (Plate XXXII, figs. 21,22; Plate XXXIIl'' 

 figs. 26, 27.) 



Localities. — Common in several parts of Britain. 



8. Pimia alata, Sig Thor, 



Male.— Ahont 0-85 mm. in length. Colour yellow, with 

 black markings. It can easily be recognised by the lanceo- 

 late form of the seminal pocket and the tongue-shaped plates. 

 The seminal pocket occupies the whole space between the 

 plates without any extra chitinous plate, such as we find 

 between the plates on P. obturbans, Pier., P. rotunda, Kram., 

 or P. rotundoides, Sig Thor. The dorsal surface is very dis- 

 tinctly marked, the Malpighian vessel being well defined. 

 The female has not yet been found in Britain, but the male 

 was found by Dr C. F. George in Lincolnshire, and my 

 drawing was made from his mounted specimen. Unfortun- 

 ately the mount was not good enough to enable drawings of 

 details of the legs being obtained, but I think the peculiar 

 shape and position of the seminal pocket are enough to make 

 us sure that it is the mite Sig Thor described and figured 

 (Plate XXXIII, figs. 28, 29.) 



9. Fiona fallax, Karl Thon. 



Female. — About 1-36 mm. in length. Palpus large and 

 strong, nearly twice as thick as first segment of first leg. 

 Genital plates tongue -shaped, with about 30 acetabula, all 

 very much of one size, to each plate. Tongue-shaped plates 

 nearly IJ times as long as broad. Width across each plate 

 about 0-56 mm. Only the female has been found up till 

 now by Dr C. F. George in Lincolnshire. My drawing was 

 made from an unmounted specimen taken by him in 1900 

 (Plate XXXIIL, figs. 33, 34.) 



10. Fiona discrepans, Koen. 



Female. — About 1-12 mm. in length, and of a yellowish 

 brown colour. Genital plates in two pairs, the anterior pair 



