112 Guide to Arachnida. 



Fam. — Tyo)nhi(liii]a('. 



Table-case The Trombidiidae are soft-skinned mites, the palpi are free, 

 No. 26. ^\^Q penultimate (or, more rarely, the last) segment being armed 

 with a claw. 



Most of the mites of this family are free-living forms, which 

 are either predatory or herbivorous. A few species are parasitic 

 upon vertebrates and insects. The species of Tromhidiwn are 

 clothed with long, red, velvety hair, and present a striking appear- 

 ance. The European representatives of the genus are of small 

 size ; in the tropics, however, large species, measuring about half 

 an inch in length, occur. The harvest-bugs, which cause irritation 

 in autumn by burrowing under the skin, are six-legged larvae 

 belonging to various species of Trombidiidae. The spinning-mites 

 {T c tr any chin ac), which occur in immense numbers on various 

 kinds of plants, cause much damage to vegetation. They spin a 

 fine web, which is usually found coating the lower side of leaves. 

 The bright glaze, which may sometimes be seen on the trunk 

 and branches of the lime tree, is produced by one of these mites 

 {Tctiron/cJi lis telarius). 



Fam. — Hi/drach n idae. 



The Hydrachuidae, or water-mites, resemble the Trombidiidae 

 closely in structure. The legs are furnished with swimming- 

 hairs. 



Most of the Hydrachnidae live in fresh water, but there are a 

 few marine species. Their food consists of small Crustacea, insect 

 larvae, infusoria, etc. They are widely distributed and there are 

 numerous British species. 



Fam. — Halacaridae. 



In the Halacaridae the buccal organs are carried on a distinct 

 rostrum ; the appendages of the first pair are either styliform or 

 chelate, and the terminal segment of the palp is conical or styli- 

 form. The skin is strengthened by a number of dorsal and ventral 

 plates. 



These mites are chiefly marine in haljit, but a few species occur 

 in fresh water. They do not swim, but crawl on algae and marine 

 animals. They were first made known by Mr. Gosse, who 

 described several British species in the year 1855. 



