Introduction to Animal Morphology. 373 



antennary jaws. Gl}-ciphagus lives on feathers, &c. Dermato- 

 dectes on horses, sheep, &c. 3. Ixodidae (ticks) — body leathery 

 •or horny, extensile, antennary feet piercers, with recurved 

 hooks ; palps 3-9, jointed, in I. Gervaisii with a sucker on the 

 last joint ; legs two-clawed ; eyes two or none. They live in 

 bushes, and attach themselves to passing animals, whose blood 

 they suck, whereupon their bodies swell immensely. The first 

 pair of maxillae, at their bases, form a kind of underlip, ring-like 

 below. The sex-openings are far forward. Argas has a rough 

 dorsal surface and two terminal hooks on the antennary feet. 

 Ixodes is smooth, dorsally, with (Hyalomma) or without eyes 

 (Amblyomma). Adenopleura, from the pangolin, has a flat- 

 tened body, a serrated hinder margin, and two lateral glandu- 

 lar sacs. The claws have an oval cushion or caruncle at their 

 base. The dorsal integument is covered with closely undu- 

 lated ridges. 4. Gamasidae, Spider mites — eyeless ; feet 

 equal, hairy, two-clawed, and with a sucking disk ; antennary 

 jaws scissors-like ; palps free, the joints equally long ; body 

 undivided ; parasitic on beetles (Gamasus), reptiles, and 

 birds (Dermanyssus), but not fastened by a piercing beak. 

 Pteroptus with a long end-joint to the palp ; lives on bats. 

 5. Oribatidas — viviparous, grass and wood mites, hard and 

 horny, cracking like glass when pressed ; antennary jaws, re- 

 tractile ; no ocelli; feet with 1-3 claws; back shield often 

 with wing-like lateral folds and two suckers at the bor- 

 der of the cephalothorax ; palps four-jointed. Nothrus 

 has a four-angled body, and thick three-clawed legs ; Phy- 

 toptus lives on vine leaves ; Leiosoma, Hoplophora, &c., on 

 other vegetables. 6. Hydrachnidae, Water-mites — legs often 

 finely bristled ; body undivided ; eyes two ; antennary jaws 

 claw-like (Atax), or sharp-pointed, needle-like (Hydrachna), or 

 bristle-like (Limnochares) ; palps short, bristled or hooked at 

 the end. The young are suctorial ; parasitic on water insects. 

 Pontarachna is marine. 7. Trombididae — soft, brightly co- 

 lored, undivided ; ocelli four (Erythraeus), or two (Tetrany- 

 chus) ; antennary jaws, claw- (Trombidium), or needle-like 

 (Tetranychus) ; palps scissors-like. Trombidium is parasitic 

 on Aphides, &c. Tetranychus telarius secretes a web on the 

 leaves of lime-trees. 8. Bdellidae — brightly colored ; body 



