114 ACAEINA OK MITES. 



least where it is scanty. It is particularly plentiful around the 

 eyes, ears, nostrils, and lips. Youatt speaks of it as "black 

 muzzle." It may spread to the belly and legs, especially the 

 hocks and pasterns. The mite is round and white, with 

 numerous spines of two sizes on the dorsal surface, and with 

 two pairs of anal bristles. Legs short ;, the two first pairs have 

 the curious suckers before referred to iu the male, the fourth 

 pair also having them ; the third pair in the male, and third and 

 fourth in the female, are armed with a long spine. This head- 

 scab is very like the itch-mite in man — in fact this form may 

 possibly be transmitted to man and other animals. The female 

 Sarcopt lays her eggs in tunnels in the skin, not under the scab 

 as in Psoroptes. Then small papules appear on the skin, which 

 on being rubbed pass out a clear exudate, hardening and form- 

 ing a crust or scab of a dirty-grey colour. The skin becomes 

 hard and deeply folded, and blood may be seen oozing out in 

 the cracks. 



The third form, Symbiotes communis v. ovis, is not of common 

 occurrence. The Symbiotes live in colonies, but do not excavate 

 any sub-epidermic galleries. They are oval, not rounded, and 

 the legs are longer and more easily seen. The legs are chiefly 

 attacked by this form of mite, similar to the attack in the horse, 

 producing red patches on the skin and very thin scabs. It is of 

 little importance in Britain. 



Varieties of Sarcoptes, Psoroptes, and Symbiotes are also found 

 on the horse, pig, ox, goat, dog, and cat, producing various 

 forms of "mange." Sarcoptes also produce the "scaly leg" of 

 fowls. 



Another form of Scabies is produced by some mites known as 

 DemodecidcB. These acari live in the hair f oUicles and sebaceous 

 glands, and produce the so-called red mange in dogs (fig. 45). 

 The same species, Demodex folliculorum, is found on man and 

 other animals. In dogs this follicular mange appears as red 

 patches around the eyes, and spreads over the body. It com- 

 mences as red spots, which gradually become purulent. In the 



