256 



PARASITIC DISEASES OP THE SKIN. 



irregularly mottled. The head is small and resembles that of 

 the common house fly in being disengaged from the thorax. 

 The legs and body are covered with minute fine hair. Its legs 

 are strong, each one being furnished with two strong, sharp 

 claws. The abdomen of the tick when filled with blood 

 from its host is immensely distended and transparent, the blood 

 being plainly visible through its texture. The male and- female 

 differ from each other, the former being a little smaller than the 



^^" 



^^iliiff^^^^^ 





Hdult Sheep Cich, «. and putsarium, b. (jvielophagus.) enlarged, after Osborn, 1896. 



latter. The eggs laid by the female are flat, ovoid in appearance 

 and of a brownish color. They are nearly one-third the size of 

 the abdomen of the parent. The eggs arc laid one at a time, 

 and are covered with a sticky dark material, securely fastening 

 them to the wool fibres. "When mature the embryo emerges 

 through an opening in one end of the shell made by the splitting 

 outwards of a portion of it, resembling a lid to a box, the young 

 insect being an exact counterpart of its progenitors, and not 

 having to pass through any intermediate stage of development, 

 so generally the case in the reproduction of parasitic life. The 

 life of the parasite is wholly spent on the body of its host. A 



