26 



A carology 



hairs. When the legs are modified so that they are no longer used for 

 walking the claws are vestigial or absent. For example, the anterior 

 pair of legs in the Macrochelidae are used as tactile rather than ambu- 

 latory organs and the claws are either minute or absent. Many of the 

 water mites that are active swimmers have no tarsal claws. 



^ ,^ 



rnf' 



Figure 25 An outline diagram of the Figure 26 A ventral view of leg i of 



male of Analges nitzschii HaWcr, IHIS Protomyobia claparedei (Poppe), 



to show the enlargement of legs iii. 1896 to show the roughened hair- 



(After Vitzthum 1940) grasping prominences. 



The legs are used primarily for walking and running but in certain 

 groups they have other functions. The tactile and swimming legs have 

 been discussed. Frequently the legs are used as graspers during copu- 

 lation. The second pair of legs of many of the Parasitidae are strongly 

 modified especially in the male (Figure 24). The males of the Anal- 

 gesidae have exceptionally developed posterior legs (Figure 25 ) . They 

 are so massive as to be useless as locomotor organs. The legs of water 

 mites have many long, closely set setae that increase their surface in 

 such a way as to make them efficient paddles. Some mites have certain 

 pairs of legs modified as hair-grasping organs (Figure 26). The pos- 

 terior legs of mites of the genera Spelorchestes and Nanorchestes have 

 specialized muscles that enable the mites to jump quite effectively. Eu- 

 podes with its enlarged femur iv is thought to be an effective jumper 

 also. 



The coxae of the walking legs of many mites are immovable and so 

 imbedded in the skin that they frequently form an endoskeleton. 



