THE ANIMAL PARASITES OF MAN 



present ("Demodicidae und Sarcoptidae," von Professor G. Canestrini 

 P. Kramer, Das Tierreich, 1899). F. V. T.~| 



uncb 



Sub-family. Sarcoptinae. 



Genus. Sarcoptes, Latreille. 



Sarcoptes scabiei, cle Geer, 1778. 



Syn. : Acarus scabiei, de Geer, 1778 j A.psoricus, Pallas, 1760 ; A. siro, L., 1778 ;. 

 Sarcoptes exulcerans, ? Linn., 1758, Nitsch, 1818 ; 5. hominis. Raspail, 1834, and 

 Hering, 1838 ; S. galei, Owen, 1853 ; S. communis, Delaf. et Bourg., 1862; S. scabiei 

 var. hominiS) Megnin, 1880. 



The body is oval or nearly circular and whitish in colour, with trans- 

 verse rows of striae partly interrupted on the back. There are trans- 



verse rows of small bristles 

 on the dorsal surface, and 

 groups of trichomae on 

 the front, sides and back. 

 There are chitinous hairs at 

 the base of the legs ; the two 

 first pairs are provided with 

 pedunculated ambulacra in 

 both sexes, the two posterior 

 pairs terminate each with a 

 long bristle in the female ; 

 in the male the third pair 

 of legs terminate in a bristle, 

 the fourth pair with a pedun- 

 culated ambulacrum. The 

 anus is situated at the pos- 

 terior border of the dorsal 

 surface. 



At one time numerous species 

 were differentiated, according to- 

 the form of the Acarus, the num- 

 ber, position and size of the hairs 

 and spines, even according to the 

 hosts, etc. All these characteris- 

 tics, however, fluctuate so con- 



siderably that absolute differentiation is impossible ; the supposed species may be 

 regarded in the same light as Megnin did, as varieties. It is also hardly possible 

 to distinguish the mite of human scabies (S. hominis) from that of a number of 

 domestic animals (S.squamiferus). It is best, therefore, to accept one single species 

 (S. scabiei\ which may give rise to different races or castes by living in the skin 

 of man and mammals, but can pass from one host to the other. 



[Canestrini and Kramer, in their monograph of the Sarcoptidcc, 

 enumerate eighteen distinct species of this genus, from the dog, goat, 



FIG. 367. Sarcoptes scabiei : female, dorsal aspect. 

 200/1. (After FUrstenberg.) 



