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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. 
T he 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. 
7 he Mandibles {or Cheliceres). —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 Rhipicepha- 
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 Eurhipicephalus and 
