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process, the hypostome. On either side of the 

 hypostome are the jointed palps or pedipalpi. The 

 hypostome, mandibles and the palps lie, as a rule, 

 closely approximated. In the genera in which the 

 palpi are long (Fig. 95), they are often found separated 

 from the rest of the mouth parts ; where the palpi are 

 very short and broad, as in Eurhipicephalus, this 

 separation is rarely seen. 



The Hypostome (Labium or Radula). The hypo- 

 stome (Fig. 95) is continuous with the chitinous 

 exoskeleton of the head. It is bilaterally symmetrical 

 and carries a number of conspicuous teeth, directed 

 backwards, and usually arranged in several rows. The 

 number of longitudinal rows of teeth is very constant 

 in the same species and is used for identification. 



The Mandibles (or Cbeliceres). Are strongly 

 chitinised organs (Fig. 95), the anterior portions only 

 of which are seen on external examination. The 

 posterior portions, which are swollen, lie in the body 

 cavity, where they receive the attachment of powerful 

 muscles. The anterior portions are rod-like and play 

 each in a sheath, formed by a prolongation forwards 

 of the chitinous covering of the head (mandibular 

 sheath). The sheaths are lined with a loose membrane, 

 and are covered externally in most cases with fine 

 ridges or teeth. At their termination the mandibles 

 carry a jointed process (digit). The digit carries 

 several processes (apophyses), which bear large hooked 

 teeth directed backwards (Fig. 96). 



The Palpi (or Pedipalpi). Are composed of four 

 segments (Fig. 95), of which the details of structure 

 vary much in the different genera. In the Rbipicepha- 

 linae the whole palp is very short, thick, and massive. 

 In the Ixodinae it is longer, and as a rule, much simpler, 

 in arrangement. In the palps of Eurbipicepbalus and 



