Introduction 



25 



phyids have only two pairs of legs in all stages, and some of the Po- 

 dapolipodidae and Phytoptipalpidae have either only three pairs of 

 legs as adults or in some cases only a single pair. 



The legs, like the palps, are usually divided into six segments which 

 extend from the body in the following order: coxa, trochanter, femur, 



Figure 23 A dorsal view of the tarsus 

 I of Haemolaelaps glasgowi (Ewing), 

 1925. 



Figure 24 Leg ii of the male of Para- 

 situs bombophiliis Vitzthum, 1930. 

 (After Vitzthum 1940) 



genu, tibia, and tarsus. Frequently the femur is divided into two seg- 

 ments, the basifemur and the telofemur, so that seven segments are 

 present. Fusion of the segments also occurs so that a five-segmented 

 leg may occur or even a two-segmented leg as is found in Schizocarpus. 

 In Chirodiscus legs i and ii consist of a single segment. In Tarsotomus, 

 on the other hand, the tarsus may be.divided into as many as eighteen 

 segments. 



The tarsi of the walking legs characteristically bear a pair of well- 

 developed claws. In addition to the claws a delicate, transparent, 

 sucker-like structure (the caruncle) may be present. A caruncle is 

 regularly found on the tarsi of the Mesostigmata and Ixodides (Figure 

 23 ) . In the Trombidiformes an empodium is frequently found between 

 the two claws and in some cases the median empodium develops into 

 a claw while the paired claws are reduced or modified to form tenent 



