450 



ARACHNIDA 



2. THYAS Koch. Like the above but with no swimming hairs on the 

 legs; body flattened: 7 species, 2 American, the larvae of which leave 

 the water and attach themselves to aerial insects. 



T. stolli Koenike. Body 1.2 mm. long, oval and red in color; legs 



with numerous bristles. 



3. DIPLODONTUS D u g e s. 

 Body oval or round; eyes 2 on 

 a side ; no median eye ; legs with 

 swimming hairs; genital plate 

 heart-shaped: 3 species. 



D. despiciens (0. F. Miiller) 

 (Fig. 707). Body 2 mm. long, 

 red in color with an indistinct 

 darker dorsal spot, and also 

 covered with papillae; larva on 

 aerial insects: common. 



Fig. 706 



Fig. 707 



Fig. 706 Hydryphantes ruber (Wolcott). 

 1, coxal plates ; 2, genital plate. Fig. 707 

 Diplodontus despiciens (Wolcott). A, ven- 

 tral aspect of male; B, pedipalp of female. 



SUBFAMILY 5. HYGROBATINAE. 



Body compact, surface smooth or with fine parallel lines, sometimes 

 with chitinous plates ; eyes of the 2 sides distant from each other, either 

 1 or 2 eyes being on a side and never in a capsule; no median eye; 

 pedipalp not chelate, or rarely so; coxal plates large, sometimes cover- 

 ing the whole ventral surface; the larva (except in Unionicola) attached 

 to water insects : 53 genera, 2 genera with about 4 species being found in 

 the sea off the coast of France. 



Key to the genera of Hygrobatinae here described : 



d Pedipalps not chelate. 

 &! Coxal plates not fused together. 



Cj, Coxal plates in 3 groups 1. HYGBOBATES 



C 3 Coxal plates in 4 groups. 

 di Fourth leg ending with a claw and not a bristle. 



i Free-swimming; fourth joint of pedipalp with 2 papillae 2. PiONA 



e a Parasitic in mussels 3. UNIONICOLA 



d t Fourth leg ending with a long bristle 4. LIMNESIA 



& a Coxal plates fused into a single plate 5. KOENIKEA 



o, Pedipalps chelate ; body of male with a posterior appendix ... 6. ABBHENUBUS 



1. HYGROBATES Koch. Body ovoid; coxal plates of female in 3 

 groups; no swimming hairs present; genital pore midway between the 

 hinder coxal plates and the hinder end of the body with 3 or more suckers 

 on each side : 11 species, 4 American. 



H. longipalpis (Hermann) (Fig. 708). Body 2.5 mm. long and yel- 

 low in color, very convex dorsally; pedipalps almost half as long as the 

 body: cosmopolitan. 



