176 RECORDS OF THE AUSTRALIAN MUSEUM. 



are never parasitic, but are vegetable feeders. Usually they are 

 oviparous, sometimes ovo-viviparous, and rarely viviparous. When 

 the young emerge they have only three pairs of legs, but in the 

 next stage they have four ; two other changes or ecdyses occur, 

 however, before the adult stage is attained. About twenty 

 genera ai-e included in the Oribatoidea, and thtse include many 

 species, but tlie group has not been touched in Australia, notwith- 

 standing the fact that quite a number of species occur, and some 

 are stored away in private collections I have seen specimens 

 from the Jenolan District. In 1897 Canestrini described several 

 from German New Guinea. Tryon has recorded one under the 

 name Leisonia, sp., from Durundur, Q., but this is the only 

 reference I can find. 



Family ORIBATID^. 

 Genus LiACARUS, Michael. 

 = Leisonia, Nicolet (nom. prceoc). 

 LiACARUS SP., Tryon. 

 Liacarus sp., Tryon, Insect and Fungus Pests, 1889, p. 160. 

 Leisonia sp., Tryon, loc. cit. 

 Hah. — Durundur, Queensland 



Family TARSONEMID^. 



There ai*e not many genera or species included in this family, 

 but some forms are of the highest economic importance. These 

 Acarids are exceedingly minute — in fact microscopic. All the 

 species are parasitic — some on vegetation, some on cereals, such 

 as grasses, rice and grain, and some on insects ; one species has 

 been found upon a mole. In Queensland, pine-apples and sugar- 

 cane are afiected. The Tarsonemidfe are soft-bodied mites, the 

 males conforming somewhat to the Tyroglyphid type ; but the 

 females differ not only from them, but from all other Acarians in 

 having a clavate organ of uncertain use between legs i. and li.^^^ 

 The mouth-parts are formed for sucking ; mandibles slender and 

 needle-like ; palpi minute, barely visible ; legs short and composed 

 of five or six joints ; anterior tarsi always terminated with one 

 claw, the others have usually two and often a sucker; the 

 posterior pairs of legs ai-e widely remote from anterior pairs ; in 



13 Banks — Loc. cit., p. 74. 



