106 



DR. A. C. OUDEMANS — A SHORT SURVEY OF 



stigmata (hence their name) in the first, second, third and fourth abdominal 

 segments. The legs on each side are contiguous. Hitherto they have been 

 found only under stones in the circum-Mediterranean countries. — Mites may 

 generally be caught by means of a small moistened paint-brush. They should 

 be preserved in small glass tubes filled with alcohol. Into the tube insert a 

 small label, on which should be noted, with black pencil or Indian ink, tha 

 locality, date, collector's name, and the conditions of capture or name of 

 the host. 



.-:• S 



(2) Tetrastigmata, or Holothyreoidea, are quickly moving Acari, with 

 brown, hard and shining integument, and as large as Lady-Birds (Cocci-^ 

 NELLiDiE). The upper surface is formed of a 

 single shield-like plate ; hence the name of 

 Holothyreoidea. 



As is suggested by the alternative name of 

 Tetrastigmata, these creatures are characterised 

 by two pairs of dorsal stigmata, of which one 

 pair is situated on the dorsal side, behind the 

 line of insertion of the fourth pair of legs, whilst 

 the other pair lies in the ventrally sufflexed 

 margins of the dorsal shield or carapace, outside 

 of the third pair of legs ; being thus apparently, 

 though not really, ventral in position (fig. 2). 

 The legs on each side are contiguous. — Hitherto 

 they have only been found under stones or on 

 the under surface of dead leaves in the followino- 

 islands : New Guinea, Ceylon, the Seychelles 

 and Mauritius. 



g'. 2. — Holothyreus longipes,. 

 Thor. ; male ; dorsal and ven-^ 

 tral side ; S = stigmata. — 

 Copied from Thorell, in Ann. 

 Mus. Genova, xviii. 1882,. 

 tab. 4. 



(3) Metastigmata, or Ixodoidea (Ticks), are 

 generally oval in shape, of varying colours, dorso- 

 ventrally compressed, and slow in their move- 

 ments ; their stigmata lie, with a few exceptions 

 (of v,'hich fig. 4 is a good example), behind the 

 fourth pair of legs, as shown in figure 3 ; hence the name of Metastigmai'A. 

 They occur as parasites, especially on mammals, less often on reptiles and 

 birds, and rarely on toads or large spiders ; but they also pass a part of their 

 life free on low herbs, or among dry and decaying leaves. — Ticks are 

 essentially blood-suckers, and their mandibles resemble in some measure a 

 pair of boat-hooks with two or more hooks ; they lie in a sheath and can be 

 protruded and retracted. The first joints, or coxcc, of the two maxilla? are 

 fused together, forming a flat rasp, which has its teeth on the ventral surface 

 (see fig. 3, underside). The mnndi1)lcs and raaxillicoxa? togftber form the 



