258 PARASITIC DISEASES OF THE SKIN. 



Lice. 



These parasites are frequently found attacking sheep. In 

 appearance the sheep-louse resembles closely the common dog- 

 louse. In length it is about one twenty-fifth of an inch, the 

 female being slightly larger than the male; its general color is 

 white, with the exception of the head, which is a reddish-brown. 



^IS$I22^ ^ 



Sbccp Louse— female. (Cricbocepbalus Spboerocepbalus.) 



*, autenna. c, d, dorsal and side view of leg, enlarg-ed. 

 (After Osborn, 1896.) 



Their life-history resembles that of the sheep-tick; the adults 

 lay their eggs at the base of the wool fibres, to which they are 

 adherent by a sticky glutinous material. The eggs hatch out in 

 the wool, the young louse emerging by pushing up a lid-like 

 contrivance of the shell. They are often found in large numbers 



