TROMBIDIID^. ORIBATID^E. SIMONEID^E. 229 



covered with hairs in such a manner as to adapt them for swim- 

 ming, and after reaching maturity they are always found free in 

 the water. They undergo a more complete metamorphosis than 

 any other Mites ; the larvae have six legs and apparently 

 a distinct head ; and the pupa: are perfectly quiescent, and 

 attach themselves to the bodies of aquatic insects or Mollusca. 

 The TROMBIDIIDJE, or Ground-Mites, are distinguished by having 

 the palpi converted into little raptorial organs. They live upon 

 the ground in crevices, and run fast. The well-known Scarlet- 

 Mite of our gardens belongs to this family. They are capable 

 of spinning little webs for the protection of their eggs ; and some 

 species are very injurious to plants in hot-houses and frames, by 

 spinning webs over their leaves. The young are parasitic, 

 usually upon insects. The BDELLIDJE, which live amongst 

 damp moss, and greatly resemble the preceding in their mode of 

 life, are distinguished by having the body apparently divided 

 into two parts, and the rostrum and palpi of great length : 

 whilst the ORIBATID./E, or Plant-Mites, are distinguished from 

 all the other Acarina, by the glassy hardness and brittleness of 

 their skins, and by the adaptation of their mandibles to the 

 purpose of biting ; their food consists of vegetable matters, 

 especially the leaves of mosses, amongst which plants they are 

 usually to be found. 



841. Besides these families of undoubted Mites, there are 

 three others which are now arranged with the Acarina by most 

 authors, but which present such peculiar characters, that their 

 title to such a position may appear somewhat doubtful at the 

 first glance. The first of these, the SIMONEID^E, includes a 

 curious minute parasitic animal, the Simonea folliculorum, which 

 takes up its abode in the follicles of the human skin, especially 

 on the nose. In the young state it is a small, elongated, 

 worm-like creature, furnished with three pairs of rudimentary 

 feet on the widened anterior part of the body ; but as it in- 

 creases in age the elongated hinder part, or abdomen, gradually 

 becomes shorter, and a fourth pair of little feet makes its appear- 

 ance. The structure of the mouth resembles that of the Mites. 

 These curious little parasites have not been discovered many 



VOL. II. S 



