THE PARTS OF A LOCUST. 



13 



just in front of the upper part of each compound eye, 

 and the third is in a hollow near the middle of the 

 face of the locust ; find each of these. 



Note. — The simple eyes are usually called the ocelli (o-cel'li). This 

 term is also applied frequently to the little eyes, or ommatidia, of which 

 the compound eyes are composed ; but if nothing is said to indicate that 

 the parts of a compound eye are meant, the term ocelli always refers to 

 the simple eyes. In the same way the term eyes usually refers to the 

 compound eyes alone. The singular form of ocelli is ocellus (p-cel'lus). 



4. Make a drawing of the front side of the head 

 showing the position of the antennas, the eyes, and 

 the ocelli. 



LESSON III. 



THE PARTS OF A LOCUST (CONTINUED). 



The Mouth-parts. 



1. Attached to the lower edge of the front side of 

 the head of the locust is a movable flap ; this is the 

 upper lip or labrum (la'bruni). Carefully remove it 

 with a knife and save it. 



2. By removing the upper lip there is exposed a 

 pair of horny jaws ; these are the mandibles (tnan'di- 

 bles). The mandibles open sidewise instead of up and 

 down like the jaws of higher animals. Carefully re- 

 move the mandibles. This can be done by separating 

 them with a pin, and turning each one sidewise till it 

 breaks from the head. Save the mandibles. 



3. By the removal of the mandibles there is ex- 

 posed a second pair of jaws, which, like the mandi- 

 bles, open sidewise. These are the ■maxillce (max- 

 il'lce). The singular form of maxillas is maxilla (max- 

 il'la). The maxillae, unlike the mandibles, are very 

 complicated organs, each maxilla consisting of sev- 



