This species is extremely common upon all sorts of dead animal and vegetable matter. In some districts it is prevalent in hay dust and farinaceous material. Megnin says that it was probably this species which Hering found upon the foot of a horse affected with canker, and which he regarded as proper to this affection; he termed it Sarcoptes hippopodus. Megnin's remarks upon its being found upon animals have already been quoted (p. 62). Garnett found it upon a sheep in a case of sheep scab (p. 64). I have recorded it from the ears of rabbits1 and guinea pigs.2 It is the cause of grocer's itch.

The small hairs upon the longer dorsal ones do not show up very clearly in the diagrams, but they are easily seen under the microscope. The apparent thickness of the longer hairs in the figures is due to their pectinated condition. The bursa copulatrix is plainly shown in Fig. 45. The hypopial nymph is not an active stage, being quite rudimentary, and never leaving the skin of the previous nymph (Fig. 48).

In some species of Glyciphagus the hypopus is homopial that is, it resembles in structure the immature form which was once regarded as a distinct genusviz., Homopus. It is chiefly in those forms which inhabit the nests of small mammals that the homopus is seen. Instead of the typical sucker plate, the ventral surface, in the same region, is furnished with a structure suitable for grasping the hair of its carrier. It consists of a median furrow with a lip or wing-like piece on each side. These can be raised or depressed by pressure, from a roughened portion on each lip near the median furrow, upon a hair in it, a secure hold being thus obtained.

1 Veterinary Journal, London, 1920, vol. lxxvi., p. 126.
2 Ibid., p. 331.

Glyciphagus cadaverum Schrank.

Syn.: G. spinipes Koch 1841. G. destructor Schrank.

FIG. 50.-GLYCIPHAGUS CADAVERUM. X 170.
Female, ventral aspect.

This species occurs in situations similar to G. domesticus, and is often mistaken for it. It commonly goes by the name spinipes. Michael gives the following points of distinction:

It has often been found upon horses by Baudét1 in Holland. In that country it occurs in hay. Megnin applied to it remarks similar to those he made upon G. domesticus (p. 62). Professor R. Newstead, F.R.S., has shown me slides labelled Mark VI. containing mites from the horse's skin which belonged to this species.

FIG. 51.—GLYCIPHAGUS ORNATUs (after NewstEAD AND MORRIS). (a) Male, ventral aspect. × 87.

(b) Tibia and tarsus of leg II. X 260.

Reproduced by permission from Report No. 8 of the Grain Pest (War) Committee of the Royal Society.

1 Baudét, E. A. R. F., "Komen chorioptes-schurftmijten in hooi of stroo voor" (Tijd voor Vergelijkende Geneeskunde Gezondheidsleer en Parasitaire en Infectieuze Dierziekten, Leiden, vol. i., p. 187).

(Fig. 51.)

Glyciphagus ornatus Kramer 1881.

This appears to be a continental species. It has been found in hay dust and moss. Newstead and Morris, in recording it from skin-scrapings from horses in France, point out that it is readily distinguished by the large comb-like appendages at the distal end of the fourth segment or tibia of legs i. and ii. of the male.