II 



forms the ventral border of the lateral part of the epicra- 

 nium. 



(a.) Vertex. — The dorsal part of the epicranium is called the 

 vertex, 



(b.) Front. — That part of the epicranium which is upon the 

 cephalic aspect of the head is termed X.\\q front. In many in- 

 sects the front is a distinct sclerite. 



(c.) GencB. — The lateral parts of the epicranium are known 

 as the gence or cheeks. 



Clypeus. — Examine again the ventral border of that part 

 of the epicranium which is upon the cephalic aspect of the 

 head. Note that the prominent suture bounding this part 

 separates it from a very broad, but short sclerite. This is 

 the clypeus. 



Labrum. — Articulated to the ventral border of the cly- 

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

 or labrum. 



Although the labrum is freely movable, it is a part of one of the segments 

 that enter into the make-up of the head-box, and not an appendage, like the 

 jaws. The true appendages of the head hold the same relation to this region 

 that the legs do to the thorax. 



Make a drawing of the cephalic aspect of the head ; and 

 name the fixed parts. 



Occiput. — Examine a locust's head which has been 

 boiled in caustic potash, cleaned, and mounted with the 

 caudal aspect uppermost. In such a preparation the soft 

 parts have been removed, and the walls of the head bleached, 

 so that the sutures can be more easily traced ; a specimen 

 of this kind will be furnished the student. 



Observe the large opening which connects the cavity of 

 the head with that of the thorax. The dorsal half of this 

 opening is bounded by the occiput. Each lateral half of the 

 occiput is triangular, with its outline well marked ; but on 

 the dorsal aspect of the head the suture between the occiput 



