REPRESENTATIVE INSECTS 345 



The grasshopper has both compound and simple eyes. The com- 

 pound eyes are situated upon the upper portion of the sides of the 

 head, and are large, oval areas with smooth, highly polished sur- 

 faces. If the eye is examined with a dissecting microscope, the 

 surface will be seen to be made up of a number of hexagonal areas, 

 which are known as facets. The simple eyes or ocelli consist of 

 three small, almost transparent, oval areas. One of the ocelli is 

 situated on the front of the head, just beloAV the margin of the 

 impression which contains the bases of the antennae, and in contact 

 with the upper portion of the compound eye. 



The antennae or feelers are two threadlike processes situated 

 median to the compound eyes. Each consists of about twenty-six 

 segments. On the front of the head there is a short rectangular 

 piece, called the clypeus, which is attached by its upper edge to the 

 epicranium, and on the lower edge to the labrum. 



The mouth parts consist of a number of separate parts attached 

 to the ventral region of the epicranium. The first noticeable part 

 is the Idhrum, or upper lip, a flaplike piece attached to the lower 

 edge of the clypeus. The free edge is deeply notched on the median 

 line. Just beneath the labrum are the mandibles, or first pair of 

 jaws. Each mandible consists of a single piece which is notched 

 on the inner grinding surface to form a number of ridges or teeth. 

 A second pair of jaws, the maxillae, may be exposed by the removal 

 of the mandibles. Each maxilla is composed of a number of parts, 

 consisting of the cardo or proximal hinge part of the structure ; the 

 stipes, the lacinia, a sclerite which bears some teeth on its terminal 

 end; the outer lobe or galea; and the maxillary palpus. The caudal 

 part of the mouth parts is the lower lip or laliium, which is composed 

 of the siibmentum which acts as a hinge on the epicranium above; 

 a mentum; labial palpi, and two large outer flaps, the ligulae (Fig. 

 200). 



The prothorax is the segment to which the head is attached. It may 

 be divided into two regions, the dorsal part known as the pronotum 

 and the ventral portion known as the sternum. The pronotum is a 

 saddle or bonnetlike piece extending over the dorsal and lateral 

 regions of the prothorax. It is made up of a fusion of four plates, 

 which are indicated by the transverse sutures. The sternum or ven- 

 tral side of the pronotum is also made up of separate plates, or 

 sclerites. The anterior sclerite bears a spine on the median line. 



