The fourth pair of

and fourth pairs of the female. legs of the male is rudimentary. (See Figs. 22 to 25.) The characteristic pedicle and sucker are shown in Fig. 24. Like the preceding genus, this group is often stated to contain one species and several varieties.

The larva has suckers on the first and second pairs of legs, two hairs on the third pair and the fourth are wanting; the nymph is larger, with an additional pair of legs

having a hair. The male (Fig. 22) has suckers on the first, second, and third pairs of legs and two abdominal lobes with hairs; the pubescent female has suckers on the first and second pairs of legs only, an ano-vulval slit and two copulatory tubercles on the posterior of the abdomen. The ovigerous female (Fig. 23) has suckers on the first, second, and fourth pairs of legs, and a transverse

tocostome.

Chorioptes equi (Gerlach 1857).

Syn.: Symbiotes equi Gerlach 1857.

C. spathiferus

Megnin 1880. C. symbiotes var. equi Railliet 1893.

The cause of symbiotic, chorioptic, or leg mange of the horse; and a predisposing factor in a number of diseases and injuries of the feet and legs.

X 117.

2. Female, ventral aspect. X 117.

3. Tarsus of leg II. of female, side view.
4. Egg. X 117.

X 250.

(Note: The fourth pair of legs in the male is shown curled up.) Reproduced by permission from Report No. 8 of the Grain Pest (War) Committee of the Royal Society.

Chorioptes bovis (Gerlach 1857).

Syn.: Symbiotes bovis Gerlach 1857. Dermatophagus bovis Furstenberg 1861.

Although this species has been found upon man (Zurn, Sheremetevsky), it probably has no clinical importance for the human subject. Habitat: bovines.

Chorioptes capræ Gervais and Beneden 1859.

Syn.: C. symbiotes var. capræ Railliet 1893.

The male measures 29 to 30 mm. long and 18 to 21 mm. broad, and the ovigerous female 31 to 36 mm. long and 21 to 23 mm. broad. Habitat: the goat.

Chorioptes ovis Railliet 1893.

Syn.: C. symbiotes var. ovis Railliet 1893.

Measurements (Zurn):

Chorioptes cuniculi (Zurn 1874).

Syn.: Dermatophagus cuniculi Zurn 1874. C. symbiotes var. cuniculi Railliet 1893.

Comparatively rare in rabbits' ears.

Although not always regarded as such, chorioptic or symbiotic mange of the horse is important on account of the number of diseases and accidents with which it is associated in starting. It is most common at the moment, usually being confined to the legs below the knees and hocks, although it may reach to the axilla

and groin. In the ox it is found on the pasterns and anal fossæ; the sheep also harbours its choriopt on the hairy portions of the legs.

The microscopic detection of the parasite is usually easy if the material is taken from the edge of an active lesion, then soaked in a 10 per cent. caustic potash solution, and finally examined between two slides under the -inch lens. The mites are often very numerous in a scraping from the lesions of an untreated case. If care is taken to thoroughly wash and dry, then to apply the paraffin emulsion mentioned on p. 30, and follow by careful sawdusting, the hair of Shire horses can be left on. As in most forms of mange, it is a question of detail, and if oily dressings are used, they must be warm, in order to get down to the actual skin; if repeated in four or five days, there is no need to previously wash, provided the animal has been kept out of the dirt. It is, however, always advisable to remove the hair from the inside of the hocks and thighs. The remarks concerning not clipping apply to the feather, or long hair of the legs, in the Shire or Clydesdale breeds.

Genus Otodectes Canestrini 1894.

Anal suckers in the male; copulatory tubercles in the female; ambulacral suckers on a very short pedicle on all legs of the male and the first and second pairs of the female. The fourth pair of legs of the female is feebly developed. (See Figs. 26 and 27.)

Habitat: the external ear of carnivora.

Otodectes cynotis (Hering 1838).

Syn.: Sarcoptes cynotis Hering 1838. S. auricularum Lucas and Nicolet 1849. Symbiotes canis Bendz 1859. Chorioptes ecaudatus Megnin 1880. C. auricularum var. canis Railliet 1893.

(See Figs. 26 and 27.) Habitat: dogs' ears.