MITES AND 800BPI0NS. 
113 
Orders of Arachnida. 
1. Body small, rounded; no distinct abdomen. Mites. 
3. Body with a jointed abdomen Arthrogastm, Scorpion. 
3. Body with a thick un jointed abdomen Araneina, Spiders. 
Order 1. Acarina, — The mites (Fig. 135) are the sim- 
plest Arachnida^ the body being oval in form^ the head 
usually small^ more or less merged with the thorax^ while 
the latter is not separate from the abdomen. The tick 
Fig. 135— Sugar-mite. Fig. 136.— Cattle-tick {Ixodes bovis). 
Much enlarged. Natural size and enlarged. 
(Fig. 136) is a large mite. It infests cattle^ sometimes 
burying itself in the skin of human beings. 
Order 2. Arthrogastra. — This group embraces the scor- 
pion (Fig. 137), the false-scorpionS;, the whip-scorpions, and 
the harvest-men {Phalangiurn). In all these forms the ab- 
domen is plainly segmented, the segments not being visible 
in the mites or spiders. Usually the maxillary palpi are 
much enlarged, and end in claws. The scorpion is vivipa- 
rous, the young being brought forth alive. The young scor- 
pions cling to the back of the mother. The sting of the 
scorpion is lodged in the tail, which is perforated, and con- 
tains in the bulbous enlargement an active poison. Though 
