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sides with lateral plates, while the anterior margin is re- 

 entrant receiving the smaller end of the pear-shaped labrum. 

 The distal part of this sclerite is membranous except for two 

 lateral chitinizations. Posteriorly it is fused with the epicra- 

 nial plate. The lateral plates are each oval and shell-shaped, 

 having their anterior lower angles produced forward and 

 united with each other. The single process thus formed pro- 

 jects forward and curves upward between the faces of the 

 posterior jaws. The tips are provided with graduated teeth. 

 In front of each lateral plate is a narrow dorso-ventral scle- 

 rite carrying the jaws. The anterior ones, mandibles^ are 

 large, strong, toothed terminally and provided on the inner 

 side with a large, softer, movable lobe. The posterior jaws, 

 maxillce^ are less strongly chitinized than the mandibles. 

 They are flat, and each is provided at its outer angle with 

 several papilla-like processes. 



