104 CRABS AND INSECTS. 
Note.—Scolopendra electra isa luminous species, and is common 
in England, Belgium, and France. It is 14 inch long, and has 140 
legs. According to Phipson, the luminosity, like that of some min- 
erals, is only evident after the insect has been exposed to the sun. 
Another luminous species is found in Asia. 
Fig. 122.—Centipede. FIG. 123.—Scolopendra Hopet. Under 
surface of head, showing poison-fangs. 
Sub-Class III.—Spipers anp Scorpions (Arachnida). 
General Characteristics.—The body is in two sections, 
cephalo-thorax, and abdomen ; four pairs of legs, simple 
eyes, and no antenne. 
Fic, 124.—Hydrachna geographica, a marine mite, and young enlarged. 
Order I. Mites (Acarina).—The mites are mostly par- 
asitic, as the cattle-tick; others are the cheese and sugar 
mites. The body is oval, and the thorax not separated 
