ACAEINA OK MITES. 123 



parasites, the hen mite is nocturnal, hiding away in crevices 

 of the walls, &c., during the day-time. Sometimes they even 

 attack the nasal cavities of the birds, and also other animals 

 to which they may become transmitted.^ 



Family Ixodidee. — The members of this family are popularly 

 called Ticks. Ixodidae are large Acari with a tough leathery 

 skin, the front of the body covered with a hard protecting 

 shield. All the ticks are blood-suckers, living some part of 

 their life upon other animals, especially warm-blooded verte- 



FiG. 53.— Head of a Tick. 

 A, Hypostome ; e, cheliceriE ; c, palpus ; d, front leg showing Haller's organ. 



brates and birds. At or near the front end is a very formidable 

 beak or capitulum (fig. 53), composed of chelicerse, and (b) a 

 sharp piercing rostrum or hypostome with recurved barbs at the 

 tip (a). When a tick is fixed on an animal it is impossible to 

 pull it off: the body comes away from the head, which is held 

 firmly fixed by the barbs in the host's skin. On the ventral 

 surface are four pairs of legs in the adult, each leg consisting 

 of six segments, the tarsus ending in a pair of claws, carried 



1 The Parasitic Diseases of Poultry, p. 52. F. V. Theobald. 1897. 



