SPTDERS AND MITES. 



221 



must put a drop of water between the plates, in order to 

 wash away the opaque granules which will escape from the 

 bodies of the animals; after which the skin, and all the 

 solid parts, will be left beautifully clear and distinct. 

 Moreover, by putting half a dozen specimens in at once, 

 we shall secure them pressed in various aspects, and be 

 pretty sure of some perfectly flat and symmetrical. 



I have one under such conditions ; the parts of the 

 mouth nicely expanded, and the whole well displayed. 

 Xoav for a high power ; for, to discern this properly, we 

 ■cannot do with less than 600 diameters. 



HEAD OF CHEESE-MITE. 



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 the 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 

 or soldered, as it were, to the sides of the lip. 



The upper portion of the mouth is formed by two stout 

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

 can be either widely expanded, or brought together, so 



