i6 



between the cardoand the proximal segment of the galea is 

 a narrow sclerite ; this is the palpifer. 



Maxillary Palpus. Articulated to the distal end of the 

 palpifer is a long, slender organ consisting of five segments ; 

 this is the maxillary palpus, 



After completing the drawing of the maxilla as a whole, 

 study the distal end of the distal segment of the maxillary 

 palpus with a higher objective, and observe the sense 

 papillae. 



Review. The mouth-parts consist of an upper lip, la- 

 bnim ; an under lip, labium ; two pairs of jaws acting later- 

 ally between these lips ; and a tongue-like organ, hypo- 

 pharynx. The cephalic pair of jaws is called the mandibles f 

 the caudal pair, the maxilla. 



NOTE. The natural attitude of the head of a locust is such that the la- 

 drum and labium appear to be fore and hind lips respectively ; and the 

 mandibles and maxilla, fore and hind pairs of jaws. But when the mouth 

 of an insect is in its more usual position, at the cephalic end of the body 

 axis, the labrum is an upper lip, the labium an under lip, the mandibles, 

 the upper jaws, and the maxillae the lower jaws. 



Each maxilla consists of six parts. These are the cardo, 

 stipes, lacinia, palpifer, galea, and maxillary palpus. 



The labium consists of the submentum, mentum, ligula, two 

 palpigers, and two labial palpi. 



THE HEAD OF A COCKROACH. 



It is desirable to supplement the study of the head of a 

 locust by an examination of the head of a more generalized 

 insect ; for this purpose a cockroach may be used. If prac- 

 ticable one of the larger species should be studied. 



Make a drawing of the ventral aspect of the head. Owing 

 to the difference in attitude the ventral aspect of the head 

 of a cockroach corresponds to the cephalic aspect of the 

 head of a locust. 



