34 VETERINARY PARASITOLOGY 
absent. The body may be oval or conical, and there 
is a marked space between the limbs, the hindmost pair 
of which often take origin even from the lower half of 
the body. 
Life-History.—Ticks pass through the usual four stages 
in the course of their existence—viz., egg, hexapod, 
larva, nymph or pupa, and finally the adult sexual stage. 
The eggs are laid on the rough pasture which the 
ticks inhabit, usually at the roots of the tufts of long 
coarse grass and bracken. As each of these hatches 
Fic. 6.—Hexapop Larva oF RHIPICEPHALUS ANNULATUS (Enlarged).* 
there emerges a white six - legged or hexapod larva, 
at first destitute of any hard covering. This larva 
proceeds to climb a convenient blade of grass, to which 
it attaches itself by its two posterior pairs of legs. When 
an animal passes, the larva fastens on to the leg with 
its anterior limbs, and crawls up out of reach of the 
bushes and foliage, which might otherwise brush it off. 
It then buries its rostrum in the skin, and sucks blood 
* After Stiles (?) compare ‘‘Moussu and Dollar’s Disease of 
Cattle, Sheep, Goats, and Swine,” p. 418. 
