SPIDERS AND MITES 



253 



I have one under such conditions; the parts of the 

 mouth nicely expanded, and the whole well displayed. 

 iNow for a higher power; for, to discern this properly, we 

 cannot do with less than 600 diameters. 



Viewed from beneath, we see a broad labium, nearly 

 square, divided at the tip into two blunt points, with a 

 sharp notch between them. The two lateral edges are, as 

 it were, buttressed by a pair of palpi, which are thick, and 

 consist of four joints each; these are distinguished by the 

 bristles at each joint, though the whole are united; sol- 

 dered, as it were, to the sides of the lip. 



The upper portion of the mouth is formed by two stout 



HEAD OF CHEESE-MITE 



mandibles, which are jointed to the front of the head, and 

 can be either widely expanded or brought together so as 

 to form a covering to the labium. They are pincer-form, 

 like the claws of a crab, the two fingers being strongly 

 toothed on their opposing surfaces. They thus form effec- 

 tive prehensile instruments. These mandibles can be ad- 

 vanced separately or together, and the whole head can be 

 elevated or depressed. 



In the water of ponds we may frequently see, playing 



