78 



THE COCKROACH 



The Head. 



The head, as seen from the front, is pear-shaped, having a semicircular 

 outline above and narrowing downwards. A side view shows that it is com- 

 pressed from front to back, with top and sides regularly rounded. The mouth, 

 surrounded by the jaws, opens below. The clypeus occupies the large central 

 part of the front, and extends ahnost completely across the widest part of the 

 face. It is divided above by a sharply bent suture from the two epicranial 

 plates, which form the top of the head as well as a great part of its back arid 

 sides. The labrum or upper lip hangs like a flap from its lower edge. A little 



Epicranial plate 



Gena- 



'^Dorsal sclerite 

 ^icranial suture 

 F enestra , ^ .Epicranial plate 

 ...Eye 



GenaT--l" 



Antenna 



Mandible 



Maxillary 

 palp 



Fig. 25. — The Cockroach (Periplaneta americana). A. Front view ; B. Side view ; 

 C. Dorsal view of the head. 



above the articulation of the labrimi the width of the clypeus is reduced. In 

 the angle so formed the anterior articulation of the mandible is situated. The 

 labrum is narrower than the clypeus and of a square shape, the lower angles 

 being rounded. It hangs down and forms the front wall of the mouth. The 

 top and back of the head are covered by two epicranial plates, which meet in 

 the middle line. The sides of the head are completed by the eyes and the gente 

 or " cheeks." The large compound eye is bounded above by the epicranium, and 

 in front, by a narrow band which connects the epicranium with the clypeus, 

 and behind, by the gena. The gena passes downwards between the eye and the 

 epicranial plate, then curves beneath the eye, and just appears upon the front 

 of the face, being loosely connected at this point with the clypeus. 



A shield-shaped aperture on the posterior surface of the head, called the 

 occipital foramen, marks the place where the neck joins the back of the head. 

 The neck itself is slender and soft, and is covered with a soft white cuticle, except 



