308 Acarology 



close to one another or more or less united with one another. Coxal 

 plate IV has a more or less long, subcutaneous process on the posterior 

 margin while the concave posterior margins of coxal plates iv form the 

 boundary of the genital indentation. The legs usually possess swimming 



Figure 239 Tiphys torris var. ameri- 

 caniis Marshall. Leg iv of male. (After 

 Marshall 1937) 



Figure 240 Fiona inter rnpta Mar- 

 shall. Venter of female. (After Mar- 

 shall 1937) 



hairs and the -tarsal claws usually have accessory teeth. The genital 

 organ has plates and six or more suckers. The suckers are seldom 

 located in the skin. In the male the sucker plates are usually united 

 with one another. The leg structure of the male usually shows sexual 

 differentiation. 



Pioninae Wolcott, 1905 



Genus and subgenera: 



Fiona Koch, 1836 



a. Fiona s. sir. 



Type. Hydrachna fuscata Hermann, 1 804 



b. Dispersipiona Viets, 1926 



Type. Hydrachna clavicornis Muller, 1776 



c. Tetrapiona Viets, 1926 



Type. Nesaea variabilis Koch, 1836 



Foreliinae Viets, 1926 



Genera: 



1. ForW/fl Haller, 1882 



Type. Hydrachna liliacca Muller, 1776 



2. Pseudofehria Soar, 1904 



Type. Pseudofehria scourfieldi Soar, 1 904 



