66 
CRUSTACEANS AND RELATED FORMS 
ing appendages. The harvestman 
(i daddy-long-legs ) is a harmless 
arachnid which does good by de¬ 
stroying inj urious insects. Spiders 
catch insects either by pouncing 
upon them or by entangling them 
in their webs. Scorpions sting 
severely, but the wound, although 
painful, is rarely fatal. Some 
ticks and mites are parasitic on man and beast. 
53. Myriapods. — Another group of arthropods is the 
Myriapoda (mir-i-a'po-da: Greek, myrioi, ten thousand; 
pous, foot), a group which includes animals of many legs 
such as the centipedes (sen'ti-pedz) and “ thousand-legged 
worms.” Centipedes are provided with poison glands, hence 
their bite is fatal to some of the smaller 
Very Common Spiders. 
animals and painful to man. The 
thousand-legged worms are harmless. 
Figure 57. — A Tropical Spider. 
Note the eight legs character¬ 
istic of all spiders. The large size 
of its legs gives it strength to carry 
away prey. 
Figure 58. — a, Thou¬ 
sand-legged Worm ; 
b, Centipede. 
Both these worm-like 
animals are members of 
the large class of Arthrop- 
oda and closely related 
to insects. 
