854 



CLASS V. ARACHNIDA. 



Pterophagus, Heteropsorus, Epidermoptes, Rivoltasia, Pachylichus, Micro- 

 lichus, Dermatium. 



Fam. 11. Tyroglyphidae. (Fig. 566.) Integument smooth and soft or 

 with low protuberances, never parallel folds ; the legs usually have a single 

 claw, often with a leaf-like but not stalked sucker. They mostly have 

 a wandering larval stage and with few exceptions, which are parasitic, live 

 amongst carrion, cheese and other organic matter. Histiostoma and 



\ 



FIG. 566. Tyroglyphus siro, seen from the ventral side. A female ; B male. Magnified 

 (from Leuckart and Nitsche). 1 Pedipalpi ; 2 ehelicerae ; 3, 4, 5, 6 first, second, third and 

 fourth walking legs ; 7 chitinous thickenings supporting legs ; 8 furrow round body ; 9 

 reproductive opening, flanked by two suckers on each side ; 10 anus ; 11 suckers at side of 

 anus. 



Nodipalpus mostly on plants or manure ; Chortoglyphus, Lentungula on 

 algae ; Aleurobius in meal ; Tyroglyphus, the cheese mite ; Histiogaster 

 on plants and fungi ; Ehizoglyphus and Hericia on the bark of trees and 

 vines ; Glycyphagiis on dust, in mole holes and moss ; Saproglyphus on 

 fungi ; Carpoglyphus on fruit and jams ; Trichotarsus in insect nests ; 

 Dermacarus on Sciurus, Pullea on beetles. 



Sub-order 6. VERMIFORMIA. 



Degenerate acarines, with no tracheae and no eyes, the posterior end of the 

 body is produced into an annulated tail. The four pairs of legs are short 

 and ^-jointed. 



Fam. 12. Demodicidae. Microscopic mites which live in the hair 

 follicles and sweat glands of certain Mammals and cause the disease known 

 as " follicular mange." The larva is legless or with very short legs. There 

 are 5 well recognized species, and several doubtful ones. Demodex folli- 

 culorum (Fig. 567) lives on man and is often seen in follicles on the nose, it is 



