PHYLUM ARTHROPODA 



243 



ment. Intermediate conditions also occur. In the Hyme- 

 noptera (bees, wasps, etc.), for example, the mouth-parts are 

 adapted both for biting and for licking and sucking ; the 

 mandibles and maxillae are sharp and lancet-like, the middle 

 part of the labium is produced into a long median tongue, 

 at the sides of which are a pair of accessory tongues {para- 



Fig. 142. — Mouth-parts of the Cockroach. lor, l^bruni; md, mandible; mx x , an- 

 terior pair of maxillae; wz, mentum; me and mi, outer and inner divisions of the 

 second pair of maxilias; pi, labial palp; pm, maxillary palp; st, stipes; sm, 

 submentum. (From Lang's Comparative Anatomy.') 



glosses). In the Hemiptera (bugs, lice, etc.) the labium is 

 modified to form a sucking proboscis enclosing the stylet- 

 like mandibles and maxillae. 



In the Diptera (house-flies, gnats, etc.) the mandibles, 



