932 



Scabies. 



The parasitic mange mites on the bodies of domestic animals are 

 divided into the three following varieties : 



1. Sarcoptes (burrowing mite). The anterior portion of the tortoise 

 shaped or roundish boily which is barely visible with the naked eye, measuring 

 0.2 to O.o mm., is forn)ed by the head, of blunt conical shape. This is provided 

 with two strong Iowim- jaws and covered from above with a chest-head shield which 

 gives it more or less a horseshoe form. The feet are short and thick, the pos- 

 terior ones do not extend over the edge of the abdomen; in the male cup-shaped 

 suckers on unjointed, fairly long pedicles are situated on the first two and the fourth 

 pairs of feet ; in the foinale on the first two pairs ; in the male the third, and in the 

 female both hind pairs of feet end in long bristles. 



The following three varieties must be considered: 



(a) Sarcoptes seabiei communis s. Sarcoptes major; in the horse, sheep, 

 goat and man; skin transversely grooved, on the back 6 long-drawn glandiform 

 thoracic, and 14 spear shaped dorsal spines arranged in 4 rows, on the posterior 

 edge of the body four strong bristles (Fig. 138). 



(b) Sarcoptes squamiferus; 

 in the dog, sheep, goat and pig; 

 the anatomical arrangement sim- 

 ilar to the preceding, consequently 

 Johne, Kitt and others considered 

 the mite as a variety of tlie Sar- 

 coptes seabiei communis. 



(c) Sarcoptes minor s. 

 notoedres; attaches itself to the 

 skin of cats and rabbits; body 



Fig. 138. Sarcoptes seabiei v. equi. Above, 



Isft, male. Below, female, from back; right, 



above, female; below, nuile, from abdominal 



side. Magnif. 75. (After :Megnin.) 



Fig. 139. Sarcoptes minor. 

 Above, female ; below, male ; 

 both from abdominal side; 

 Magnif. 75. (After M^gnin.) 



roundish, without thoracic spines, only 12 dorsal S])ines; back without scales, skin 

 concentrically grooved (Fig. 139). 



The sarcoptes mite penetrates under the skin by the aid of its powerful 

 jaws and head, and inunediately digs a tortuous passage above the papillae of the 

 cutis, in which the female always penetrates further to lay her eggs, wliile 

 the male takes up Ins aliode superficially in the neighliorliood of the opening of 

 the burrow or wanders at)out on the surface of the skin. 



2. Dermatocoptes (rsoroi)tes, Dermatodoctes, sucking mites). These have 

 ovoid bodies 0.5 to (t.S iiun. long, nuich larger than those of the burrowing mite and 

 readily perceptible to the naked eye. The head is longer than broad, pointed, the 

 lower jaw is straight, suitable for ])uncturing, the back without spines and scales, 

 with two strong shoulder bristles, slightly grooved, the feet long; all four pairs in 

 the male and the 1st, 2d and 4th pairs in the female end in tulip shaped suckers, 



