CLASSIFICATION 3 
Arachnida.—Terrestrial. Usually two regions, cephalo- 
thorax and abdomen; though various Acarina have but one 
and Solpugida have all three—head, thorax and abdomen. 
Cephalothorax unsegmented, bearing two pairs of oral append- 
Fic. 3. 
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Peripatus capensis. Natural size.—After Mose Ley. 
ages and four pairs of legs. Abdomen segmented or not, 
limbless. Respiration tracheal, by means of book-leaf tra- 
cheze, tubular tracheze, or both; stigmata almost always abdom- 
inal, at most four pairs. Heart abdominal in_ position. 
Example, Buthus (Fig. 2). 
Malacopoda. — Terrestrial. Tee 
Vermiform (worm-like), unseg- 
mented externally. One pair of 
antennz, a pair of jaws and a 
pair of oral slime papille. Legs 
numerous, paired, imperfectly 
segmented. Respiration by means 
of tubular trachez, the stigmata 
of which are scattered over the 
surface of the body. Numerous 
nephridia (excretory) are pres- 
ent and these are arranged seg- 
A diplopod, Spirobolus marginatus. 
mentally in pairs. Two separate Sie eet 
longitudinal nerve cords, con- 
nected by transverse commissures. Integument delicate. A 
single genus, Peripatus (Fig. 3), comprising many species. 
Diplopoda.—Terrestrial. Two regions, head and body. 
Body usually cylindrical, with numerous segments, most of 
which are double and bear two pairs of short limbs, which are 
inserted near the median ventral line. Eyes simple, antenne 
