86 Mites Injurious to Domestic Animals. 



that Demodex was in this case associated with a skin complaint due 

 to some other mite such as Sarcoptes or Psoroptes. 



Demodex cati, Megnin, 1880. 



(Fig. 50 e.) 



Body elongated, the abdomen of the male pointed at the end. 

 Demodex cati occasionally causes a skin disease very like that of 

 the follicular mange of the dog. It may also be present in notoedric 

 mange or in cases of parasitic otitis due to the mite called Otodectes. 

 Specimens have been found in the skin of cats which were appa- 

 rently quite healthy and showed no sign of any skin complaint. 



Demodex caprae, Railliet, 1895. 



The demodectic mange of the goat is characterised by little 

 pustules varying from the size of a pea to that of a walnut. Some- 

 times they are placed on the surface of the skin, but in other cases 

 they are situated deeply and are not visible on the surface. These 

 pustules contain a greyish matter with numerous specimens of 

 Demodex in all stages of development. The more deeply situated 

 nodules are only visible when the skin is taken off (for they are 

 situated on the inner surface) ; when the skin is being tanned holes 

 appear at the places where the nodules occur and greatly lessen its 

 value. In certain parts of Germany, according to Rissling, the 

 goats of the race of Saanen are especially affected with this com- 

 plaint ; in many villages the majority of the goats have con- 

 tracted it, whilst in other localities it is unknown. 



SUB-ORDER MESOSTIGMATA. 

 FAMILY GAMASIDAE (PARASITIDAE). 



These mites usually have rather strongly chitinized plates on 

 the body. There is a well-defined linear peritreme running down 

 each side of the body, the stigmal opening being placed close to 

 the basal joint of the last pair of legs,, Many of the mites of this 

 family are free-living, often predatory forms ; others attach them- 

 selves to beetles and other insects for transport ; others are para- 

 sitic on small mammals, often living in the debris of the sleeping 

 place or nest of the host, others are found on birds or reptiles. 



The species of Halarachne live in the bronchial passages of seals, 

 whilst those of the genus Pneumonyssus inhabit little cysts or 

 tubercles in the lungs of old-world monkeys. 



