BURROWING-MITES. 53 
body; the ambulatory suckers are carried on a long tri- 
articulated pedicle; the male has copulatory suckers and 
abdominal prolongations. 
3. Sueking Iteh-mites (Symbiotes), which live only 
upon the surface of the skin, but which penetrate with their 
mandibles through the upper skin to suck blood, lymph and 
serum. Usually they can not thrive upon the human skin, 
though cases have been reported in which species infesting 
sheep invaded successfully another host, man. 
These mites have an oval body; beak slightly conical, as 
wide as long, and destitute of cheeks; the legs long, thick, 
and visible beyond the sides of the body; the ambulatory 
suckers are very wide and carried at the end of a simple and 
short pedicle; the male has copulatory suckers, and more or 
less developed abdominal prolongations. 
1. Burrowing-mites (Sarcoptes).—This genus con- 
tains two sub-genera, one infesting mammalia, the other, 
birds. The former contains two species, the common itch- 
mite (Sarcoptes scabiec De Geer), and the dwarf itch-mite 
(Sarcoptes minor Fuerst.). 
The common itch-mite (Sarcoptes scabiei De G.) is found 
on man and on a large number of mammals, where it causes 
the ordinary itch or mange. The parasite varies according 
to the species of mammals upon which it lives, and not alone 
in dimensions, but even in secondary anatomical details. 
Formerly these varieties were described as so many species. 
The following varieties are found upon our domesticated. 
animals: 
MANGE OF HORSE (\S. scabiei var. equ). 
SCAB OF SHEEP (S. scabiei var. ovis). 
SCAB OF GOAT (S. scabier var. capre). 
SCAB OF PIG (WS. scabiei var. suis). 
MANGE OF DOG (SW. scabiei var. canis). 
MANGE OF WOLF (S. scabied var. lupt). 
According to Fuerstenberg this last variety causes the 
Norwegian itch mentioned later. 
