104 



CRABS AND INSECTS. 



NOTE. Scolopendra electro, is a luminous species, and is common 

 in England, Belgium, and France. It is i 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. 



FlG, 123. Scolopendra Hopei. Under 

 surface of head, showing poison-fangs. 



Sub-Class III. SPIDERS AND SCORPIONS (Arachnida). 



General Characteristics. The body is in two sections, 

 cephalo-thorax, and abdomen ; four pairs of legs, simple 

 eyes, and no antennae. 



FIG. 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 



