1906-1907.] British HydrachnidcB : The Genus Fiona. 373 



Bremen proposed the name of Curvipes, on account of the 

 peculiar formation of the patella segment of' the fourth leg of 

 the male. This does not appear to be a very good name, 

 as it is based on a characteristic pertaining to one sex only. 

 The name was adopted by all subsequent writers on this 

 genus, including Dr Piersig and Dr Wolcott. Dr Piersig, 

 however, in ' Das Tierreich,' made another alteration, by 

 rejecting Curvipes and substituting in its place Fiona, — a 

 generic name proposed by Koch in 1842. There is a doubt 

 in some minds as to what species Koch intended to include 

 in this genus. For some time quite another group of species 

 was ranked under that generic name, — species with only 

 three acetabula on each genital plate. However, if Fiersig 

 is right, and what we are considering as Fiona are really 

 what Koch intended to include in this genus, his name should, 

 of course, have priority over any proposed since. 



It is not here proposed to go into this question any further, 

 but to use the generic name of Fiona. So long as the generic 

 characteristics are distinct and easily understood, it does not 

 appear of much consequence what name is used. 



The genus Fiona contains a number of well-defined species 

 whose points of identity are fairly well understood. These 

 species exhibit a great diversity in size and colour, but are not 

 so interesting in structure as some belonging to other genera. 

 The body length varies from a little over half a mm. to nearly 

 three mm., and in colour we get all shades of red, blue, yellow, 

 and green. They appear to be very common in most ponds 

 and small rivers, and when captured there is generally a large 

 number of one species taken. They are strong and active, and 

 appear to feed on any small animal or vegetable matter which 

 comes in their way. 



It was during the year 1899 that members of this genus 

 were first recorded for Britain, eleven species being figured 

 and described. — (See 'Science Gossip' for 1899.) Since then 

 a number of other species have been recorded, so that we 

 have now nearly double that number. In 1899 they were 

 all described under the name Curvipes, for reasons already 

 mentioned. 



The species of this genus vary greatly, — so much so that 

 without examination of all the points of identity it is fairly 



