Hydrachnellae 



287 



coxal plates are contiguous. In the female the genital organ separates 

 coxal plates iii and iv; in the male coxal plates iv touch medianly and 

 the genital organ is posterior to these. United plates i form a cam- 

 erostome into which the gnathosoma can be withdrawn. Trochanters 

 I, II, and III have a strong, cuplike cavity into which the basifemora 

 articulate; the tarsal claws are strongly sickle-like and lack accessory 

 claws but have a sharp tooth on the concave side. There are two mov- 

 able genital plates which are divided into anterior and posterior parts, 

 the posterior portion having many small genital suckers. These mites 

 are to be found living in hot springs. 



Genus: 



Thermacarus Sokolow, 1927 



Type. Thermacarus thermobius Sokolow, 1 927 



Discussion: These mites are to be found living in hot springs whose 

 temperatures range from 42° to 46° C. 



Reference: 



Marshall, R. 1928. A new species of water mite from thermal springs. 

 Psyche 35 (2) : 92-96. 



Rutripalpidae Sokolow, 1934 



Figure 210 



Diagnosis: The skin of these 

 mites is weak, with a tendency to 

 form sclerotized platelets or pa- 

 pillae. The coxal plates are di- 

 vided into four groups of two 

 each. There are no swimming 

 hairs on the legs; the first three 

 pairs of legs have well-developed 

 tarsal claws provided with many 

 narrow accessory spines (on leg 

 IV these accessory spines are al- 

 most entirely reduced). From a 

 lateral view the two end segments 

 of the palps seem shovel-like and 

 broadened. The fixed chela of the 

 chelicera is reduced. 



Figure 210 Rutripalpus limicola Sok- 

 olow. Venter. (After Sokolow 1934) 



