jj. Porose areas elongate, shield brown, in the female with an apical silvery mark, in the male with two small and two or four other silvery spots; shield of the female longer than broad (fig 158 e). A. AMERICANUM. [Illustration: 153. Rhipicentor bicornis, ventral aspect, male. After Nuttall and Warburton.] cc. Hypostome small, without teeth, venter without furrows; body often with coriaceous shields, posterior margin of the body never crenulate (i.e. without festoons); no eyes. GAMASOIDEA. d. Parasitic on vertebrates; mandibles fitted for piercing; body sometimes constricted. DERMANYSSIDÆ. e. Anal plate present. DERMANYSSINÆ. f. Body short; legs stout, hind pair reaching much beyond the tip of the body. On bats. _Pteroptus_ Dufour. ff. Body long; hind legs not reaching beyond the tip of the body. g. Peritreme on the dorsum, very short; body distinctly constricted. _Ptilonyssus_ Berl. gg. Peritreme on the venter, longer; body not distinctly constricted. h. Mandibles in both sexes chelate. Parasitic on bats, mice and birds (fig. 150, h). LIPONYSSUS Kol. The species L. (= LEIOGNATHUS) SYLVIARUM frequents the nests of warblers. An instance is on record of these mites attacking man, causing a pruritis. hh. Mandibles in the male chelate, in the female long, styliform (fig. 158 j). Parasitic on birds. DERMANYSSUS Dug. Two species of importance may be noted, _D. hirundinus_ and D. GALLINÆ. The latter (fig. 51) is a serious pest of poultry, sometimes attacking man, causing itching and soreness. ee. Anal plate absent. In lungs and air passages of some mammals. HALARACHNINÆ. dd. Free or attached to insects, rarely on vertebrates. e. First pair of legs inserted within the same body opening as the oral tube; genital apertures surrounded by the sternum. On insects. UROPODIDÆ. [Illustration: 154. Rhicephalus sanguineus, male. After Nuttall and Warburton.] ee. First pair of legs inserted at one side of the mouth opening; male genital aperture usually on the anterior margin of the sternal plate. GAMASIDÆ. This family contains a number of genera, some of which are found upon mammals, though the majority affect only other arthropods. One species, LÆLAPS STABULARIS, frequents the bedding in stables, and in one instance at least, has occasioned irritation and itching, in man.