PARASITOLOGY. 49 



the leaves of veg^etation by man or animal, when it 

 buries itself in the skin and produces intense itching. 

 Treatme?ii. — If the affected part be touched with a 

 one-percent solution of formalin it will kill the para- 

 sites and stop the itching; or, the parts may be 

 touched with a two-percent solution of aqua ammo- 

 nia. 



SARCOPTIDAE. 



The three principal genera of the sub-family Sar- 

 coptidae are : 



Sarcoptes (Sarco — flesh; kopto — to cut). 



Psoroptes (Psora— itch). 



Symbiotes (Sym — togather; bios — life). 



The Sarcoptes live on the body where the hair is 

 short, — in horses and dogs on the body ; in sheep, on 

 the facial regions. 



The Psoroptes live on the body where the hair is 

 long, — in horses and cattle in the mane and down the 

 back ; in sheep, on the body. 



The Symbiotes live on the extremities, — legs. 



GENERAL DESCRIPTION OF THE FAMILY. 



Minute in size; the body is oval and obtuse at both 

 ends, convex above and flat below ; the mouth parts 

 are provided with a single lancet-shaped piece, sur- 

 rounded by palpi ; the legs are divided into five arti- 

 cles each, the free extremity of the last segment 

 is provided with an ambulacrum or one or two hairs. 



The genus Sarcoptes, species Scabei, is provided 

 with a head as broad as it is long ; the rostrum is 

 short, and is margined by two cheeks. 



Male,— The first, second and fourth pair of legs 



