16 



Arachnida and Myriopoda 



The mite is found at the extreme end of the burrow, and if this is 

 slit open with a fine needle the parasite can often be extracted 

 without any difficulty, owing to the fact that it is apt to cling to 

 the point of the needle by the suckers of its feet. 



The Itch-mite is very minute, appearing to the naked eye as a 

 tiny whitish speck. The female is 330-450 [x in length. If 



,' • : '- ' 



•- .■ mm 



Pig. 5. 



Sarcoptes scabiei. s. Adult female at end of gallery, 

 ce, ce', ce," Eggs in various stages of development, 

 c, Empty egg shells. o, Opening through which a 

 larva has escaped, e, Excrement. (Prom Railliet, 

 partly after Gerlach.) 



examined under a moderately high power of the microscope it is 

 seen to be shaped rather like a tortoise, the upper surface being 

 convex and the legs short, the posterior ones ending in long- 

 bristles, Numerous denticles and some symmetrically placed 

 processes are present on the upper surface. The period of incuba- 

 tion of the egg seems to be from four to eight days. As is usual 



