66 



PARASITOLOGY. 



to have four pair of legs. Another moulting brings 

 the larvae to the pupal stage, with legs fully devel- 

 oped, and after still another moult they are sexually 

 mature. 



Of the varieties of Demodex Folliculorum enumer- 

 ated only two are common in the United States. 



Demodex Folliculorum, variety Canis. 

 History. — Fir.^t studied in Europe. It is common 

 in many localities of the United States. 



