146 
ON THE SARCOPTES OF MAN 1 . 
By P. A. BUXTON, M.A., 
Fellow of Trinity College , Cambridge. 
{From the Quick Laboratory , University of Cambridge.) 
(With 9 Text-figures.) 
Our knowledge of the systematics of the genus Sarcoptes is in an unsatisfactory 
state. About a score of species have been admitted, many of which have never 
been seen since they were described. Many of the descriptions date from 
between sixty and seventy years ago, a period when microscopes and micro¬ 
scopical technique were barely adequate to cope with so difficult a genus as 
Sarcoptes is. In order to provide a basis for further study of Sarcoptes , War- 
burton (1920) published a critical survey of our knowledge regarding these 
mites. His review of the literature has proved invaluable to myself, and is 
the foundation on which I have worked. In the foregoing paper (pp. 114-145) 
I published an only too lengthy description of the Sarcoptes of the horse, 
finding that a full description of one form was necessary as a basis for com¬ 
parison. Since we do not know what anatomical points are of systematic 
importance, attention was given to all details of the external anatomy. 
I propose to deal now with the Sarcoptes of man. It is commonly held that 
the “itch” is caused by a species or variety peculiar to the human race 
{Sarcoptes scabiei var. hominis (Hering)) and that this mite is separable on 
anatomical grounds from the sarcopts of other animals; it is believed that 
man is also attacked by “S. scabiei-crustosae ” Furst., and that this mite, which 
produces symptoms graver than those of itch, is a “good species,” separable 
from S. scabiei and from the species attacking quadrupeds by definite ana¬ 
tomical characters. This second sarcopt is however very little known, and the 
“Norwegian Itch” or “Crusted Scabies,” of which it is the cause, is a rare 
disease. 
1. Sarcoptes scabiei var. hominis (Hering). 
In comparing the common Sarcoptes scabiei of man with that of the horse 
particular attention has been devoted to the characters on which previous 
authors separated their species and the following conclusions have been reached. 
Canestrini and Kramer give 300-450 by 250-350 microns as the dimensions 
1 Investigation carried out with the aid of a grant from the Ministry of Agriculture and 
Fisheries. 
