492 



AKACHNIDA. 



Oribatidce, oviparous, 

 three pairs of legs, 

 the HydrachnidcB is 

 stages (fig. 382 a, b). 

 and plants, others are 

 in water. 



The young are usually hatched with only 

 and undergo a metamorphosis, which in 

 distinguished by several larval and pupal 



Very many Mites are parasitic on animals 

 predacious and live some on land and others 



Fam. Dermatophili. Small elongated mites with long vermiform, trans- 

 versely ringed abdomen, with suctorial proboscis, stylif orm jaws, and four pairs 

 of short, two-jointed stump-like feet. The only known genus, Demodex 

 (Simonca), lives in the hair follicles of domestic animals (Dog, Cat, Sheep, 

 Cow, Horse), and as D. folliciilorum Sim. in the hair follicles of Man, where 

 they may give rise to comedones (fig. 384). 



Fam. Sarcoptidae. Itch mites. Body microscopic in size, stout, and with a soft 

 skin, with chitinous rods for the support of the appendages. 

 There are no eyes. The oral apparatus consists of a suc- 

 torial cone with chelate chelicerge and short laterally-placed 

 pedi palpi. The legs are short and 

 stump-shaped, and some or all of 

 them have stalked suctorial discs. 

 The males often have suckers and 

 processes at the posterior end of 

 the body. The females have a 

 special vulva and receptaculum 

 seminis. They live upon or in 

 the skin of Vertebrates, and occa- 

 sion the itch and mange. Sar- 

 coptes scabiei Dug. (fig. 385), itch 

 mite. With numerous pointed 

 tubercles, spines and hairs on the 

 dorsal surface. Legs five-jointed, 

 the two anterior terminate with 

 stalked sucker ; the last pair of 

 legs in the male ends not, as in 



., the female, in a bristle, but in a 



FIG. 383. Female of Phytop- 



P us vitii, from the leaf of stalked sucker (fig. 385). The 



the vine (after H. Lan- females only bore deep passages Fio. 384 Demodex 



dois). Ov, Ovaries; A, i n the epidermis, at the end of 



##SKZX W '" '^ ' -d produce by 



pair of legs their pricking the skm disease 



known as the itch. The young, 

 when hatched, possess only three pairs of legs and undergo several moults. 

 The domestic animals are infected by different species of Sarcoptidce, which 

 may be temporarily transferred to man. Dcrmatodectes communis Fiirst. Sym- 

 Uotes equi Gerl. (fig. 386). 



Fam. Tyroglyphidae. Cheese-mites. Of more elongated form, with conical 

 proboscis, chelate chelicerae, and three-jointed pedipalpi. The five-jointed legs 

 are tolerably long, and have lobes for attachment and claws. Large suckers, 

 especially in the male, are often present at the sides of the anus. They live 

 on animal and vegetable matters. Tyroglyphvs siro Gerv. Rhizoglyplius 



A 



folliculorum (after 

 M^gnin), strongly 

 magnified ; Kt, 

 pedipalpus. 



