THE ACARINA OR MITES. 



53 



The genus Fiona (figs. 93, 94) ( Curvipes) is also a large genus, and about 19 species are 

 now known in North America. In appearance they are similar to Atax. They occur 

 chiefly in lakes and ponds. The fourth joint of the palpus usually has two papillae 

 beneath, and the legs are well provided with s^^^.mmi^g hairs. The genital aperture 

 is much in front of the hind margin, and each side of it are a great number of sucking 

 disks, often of two sizes. In the males of some species one or two joints of the hind 

 legs are enlarged or produced at the tip. 



Fig. 93.— Fiona sp., and palpus above, 

 thor's illustration.) 



(Au- 



FiG. 94.— Larva of Fiona. 

 tration. 



(Author's illus- 



The typical genus, Hydrachna,^ includes a number of globose mites of moderate size, 

 the legs with swimming hairs, the palpi slender, ^vith the last joint very short, similar 

 to Tromhidium. 



Feliria is similar in appearance to Atax, but there is a lai^e plate on each side of the 

 apex of the venter bearing many disks. In the male these plates are united. Some 

 of the species occur in wet moss, but many in mountain streams. 



Fig. 95.— X;ai sp. (Author's illustration.) 



Fig. 96.— Coxal plates of ^/ai. (Author's 

 illustration.) 



In Hydrochoreutes the legs are very long, sometimes three times as long as the body, 

 which often protrudes considerably in front of the mouth parts. The genital appa- 

 ratus of the male forms a slender terminal petiole ; the female is very much larger than 

 the male. 



1 The type of Hydrachna was fixed by Latreille in 1810 (Consid. gen.) as H. 

 did not give type to Hydrachna (nor any old genus) in his Precis (1796). 



?ogTapMcum Miiller. lie 



