SriDEKS AND MITES. 



255 



Tlie upper portion of the moutli is formed by two 

 stout mancUhlcs^ which are jointed to the front of the 

 licad, and can be either widely expanded or ])ronght 

 together so as to form a covering to the labium. Tliey 

 are pincer-fonn, like the claws of a crab, the two fin- 

 gers being strongly toothed on their opposing surfaces. 

 They tlins form effective prehensile instnimcnts. These 

 mandibles can be advanced separately or together, and 

 the Avhole head can be elevated or depressed. 



HKAD or CIIEESE-MITE. 



In the water of ponds we may frequently see, play- 

 ing among the sub-aquatic vegetation, bright-coloured 

 Mites ; sometimes rich velvety green, sometimes pur- 

 ple, but more commonly brilliant scarlet ; often curi- 

 ously marked with sinuous patterns or spots of black. 

 They swim rapidly and evenly by means of rapid row- 

 ings with their legs, which are thickly fringed with 

 long hairs. I have one here, which seems to be the 

 Ihjdrachna Mstrionica. It is a little, flat, circular, 

 cushion- or cake-like creature, scarlet, with four clouds 



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