260 ANNULATA. 
and sucking. The best known are skin-parasites (or ecto- 
parasites) upon various animals. The type shown is a 
mange-mite which tunnels in the skin of the domestic 
animals, and gives rise to the painful “itch” or skin mange. 
Other Arachnida are the little long-legged “ harvest- 
men,” the book-scorpions and certain parasites. Lastly, 
there is an interesting animal, the king-crab (Limulus), 
which lives in mud of shallow seas in the Oriental region. 
It breathes by gill-books and has a large cephalothoracic 
shield, six pairs of chelate appendages and a long post- 
anal spine. It appears to be an aquatic Arachnid of very 
primitive character. 
Fig. 183.—THE HARVESTMAN 
(Phalangium cornutum). Magnified. 
(TABLE. 
