— 14 — 



THE MOVABLE) PARTS OP THE HEAD. 



Under this category are classed a pair of jointed append- 

 ages termed the antenna? and the organs known collectively 

 as the mouth-parts. 



Antennae. — Just cephalad of each compound eye there is 

 attached to the head a long, thread-like, many-jointed ap- 

 pendage. These are the antenna?. Each antenna is situated 

 in a depression which is known as the antennary fossa. 



Mouth-Parts. 



Labrum — Articulated to the ventral border of the clypeus 

 is a broad, freely movable flap. This is the upper lip- or 

 labrum. . 



Letter this part in the drawing of the cephalic aspect of 

 the head. 



Mandibles. — Carefully remove the labrum. By doing 

 this there is exposed a pair of jaws which open by a meso- 

 lateral motion of each jaw. These are the mandibles. Each 

 mandible consists of a single short and thick piece, the distal 

 extremity of which is notched so as to form a series of teeth. 



Remove the mandibles. This may be done by separating 

 them with a pin and turning each one laterad until it breaks 

 from the head. 



Make a drawing of one mandible. 



Maxillae. — By the removal of the mandibles there is ex- 

 posed a second pair of jaws which, like the mandibles, open 

 by a meso-lateral motion. These are the maxilla?. Unlike 

 the mandibles the maxillae are very complicated organs. We 

 will return to them later. 



Labium. — Remove the head of the locust and pin it with 

 the caudal aspect uppermost to a piece of cork. 



Note the freely movable flap which is the caudal part of 

 the mouth-parts. This and the crescent shaped piece to 

 which it is attached form the lower lip or labium. 



