124 



ACAEINA OR MITES. 



on a slender stalk, and in some with a membranous puhillus 

 between. On the anterior tarsi (fig, 54, /) is a narrow pit lined 

 with sensory hairs (Haller's organ), probably olfactory (/). The 

 sexual opening (j) in both sexes is on the ventral surface not far 

 from the capitulum ; the anus (k) is farther back. Ticks have 

 spiracles (h), which lie behind and above the bases of the third 

 or fourth pair of legs. The male tick is smaller than the female, 

 and its body does not swell much. The hind part of the female's 



-ExTKRNAi PARTS ov A Tit K. (After Wheeler.) 



a, Hypostorae ; h, palpus ; c, clielicerte ; d, capitulum ; c, rostrum ; /, Haller's organ ; 

 fj, seutellum ; h, spiracle ; i, peritreme ; ,/, genital opening : k, anus ; /, anal groove ; 

 VI, genital groove; n, cephalotliorax ; n, fringe or marginal indentations; j', coxa; 

 y, trochanter ; r, femur ; s, tibia ; f, tarsus. 



body is capable of very considerable distension, although tough. 

 Ticks are found amongst grass, shrubs, and especially on sandy 

 soil. When young they are quite small creatures, but very 

 active. They are then six-legged, and are known as Seed or 

 Grass Ticks. They crawl about over the grass and vegetation, 

 and eventually get fixed on to some passing mammal or bird, 

 from which they instantly commence to suck blood. During 

 this temporary parasitism the body swells, owing to the quantity 

 of blood taken in. When the larval tick has completed its 



