384 British Hydrachnidce : The Gemis Fiona. [Sess. 



15. Fiona rufa, Koch. 



Female. — About 1'30 mm. in length. Colouring of this 

 species varies very considerably. There is one variety a 

 bright scarlet with black dorsal markings and yellow legs ; 

 another is of a beautiful cerulean blue ; while there have also 

 been found brown and green specimens. The locality, no 

 doubt, has a great deal to do with this. Body rather 

 narrow, and markings on dorsal surface very distinct. 

 Eyes large, and each surrounded by a light patch of 

 colour, much lighter than the other parts of dorsal surface. 

 Chitinous parts always of a different colour from the body, 

 making this mite a very beautiful object from a colour 

 point of view. Legs long and thin, and well supplied with 

 swimming -hairs. Palpi not quite so wide as trochanters 

 of first legs. Two hairs on flexor edge of fourth segment 

 of palpi rather close together. Genital plates sickle- 

 shaped, with a large piece of the anterior portion cut 

 away, leaving four plates, two on each side of genital 

 aperture ; anterior plates each with one acetabulum and 

 some hairs, and the posterior plates with about 8 or 10 

 acetabula each. 



Male. — About 0'60 mm. in length, with from 8 to 12 

 acetabula on each genital plate. Seminal pocket more dis- 

 tinctly marked than P. conglobata, Koch, with the anus well 

 behind the plates. There are three long swimming-hairs at 

 distal end of patella, and a straight-pointed claw to tarsus 

 of third leg. (Plate XXXIX., figs. 66-72.) 



Localities. — Common. 



16. Fiona ciradaris, Pier. 



Female. — About 1"30 mm. in length, of a pale straw 

 colour. Genital plates sickle-shaped, each divided by a space 

 into an anterior and posterior plate ; each posterior plate with 

 from 12 to 14 acetabula. 



Male. — About 0'82 mm. in length. Colour, a pale straw 

 yellow, as in female. Seminal pocket cherry - shaped, 

 broader than long, with about 12 acetabula on each plate. 



