THE MITES 103 



coincides with varieties which have unimportant and scarcely dis- 

 tinguishable differences. There is, therefore, but one species, Psoroptes 

 communis, designated according to host as variety ovis of the sheep, 

 var. bovis of the ox, var. equi of the horse, var. cuniculi of the rabbit, 

 etc. 



Chorioptes (Symbiotes; Dermatophagus) (Fig. 67). Sarcoptidae 

 (p. 101). — The body is oval. The mouth parts are about as broad as 

 long and somewhat dome-shaped. The legs are long and visible beyond 

 the sides of the body. The ambulatory suckers are large and carried on 

 short, unsegmented stalks. In the female all of the legs are terminated 

 by suckers excepting the third pair, these are terminated by bristles. 

 The male has copulatory suckers and abdominal prolongations ter- 

 minated by leaf-like processes. The fourth pair of legs is stunted; all of 

 the legs are provided with suckers. 



Chorioptic mites live, as do psoroptic, in colonies upon the skin where 

 the hair is long and among the crusts which they form. There is one 

 species, Chorioptes communis (Symbiotes communis, Chorioptes symbiotes, 

 Dermatophagus communis). This infests the lower parts of the legs, 

 especially of horses with long hairs upon the fetlocks, though in the ox 

 this form of scabies generally has its seat at the base of the tail. 



Cnemidocoptes (Sarcoptes). SarcoptidiP (p. 101). — The body is 

 rounded in outline. The mouth parts are short, broader than long, and 

 rounded. In the female the legs are conical and very short; they are 

 without suckers or bristles, terminating in two unequal booklets. In 

 the male the legs are somewhat longer and all four pairs are terminated 

 by stalked suckers and bristles. 



This genus contains a burrowing mite, Cnemidocoptes mutans (Fig. 74), 

 which produces "scaly leg" in fowls; also a species known as the de- 

 pluming mite, Cnemidocoptes gallince, which attacks the skin of fowls 

 near the insertion of the feathers. 



Of the genera Notoedres (Fig. 71) and Otodectes, the former infests 

 small mammals, and the latter lives in the external ear of the dog and 

 cat. 



Family IV. Demodecid.e 



Acarina (p. 94). Follicular mange mites (Fig. 70). These are verj' 

 minute and worm-like. The body is distinctly divided into cephalo- 

 thorax and abdomen, the latter elongated and transversely striated. 

 The anus is on the anterior ventral border of the abdomen, probably 

 serving in the female for both, copulation and ovulation. The legs are 

 three-segmented, short and stumpy. The mouth parts are suctorial. 

 Respiration is cutaneous. There are no e.yes. The length is about 

 0.3 mm. 



They undergo the same stages of development as other acari. 



