INSECTA 



115 



that, as in the lobsters, there are instar periods separated by 

 ecdyses. 



The head is flexed below the thorax, and, like the body, it 

 is flattened. Laterally the surface is occupied by the large 

 compound eyes. Between them the surface is divided into 

 the epicranium and the clypeus, to which is hinged the front 

 lip, or labrum, depending like a curtain in front of the mouth. 



Head 

 Pronotum 



Elytron 



Cercus 



FIG. 55. Blatta. Male (left) and female (right). 



Two pale spots on the epicranium, close to the antennae and 

 at the ends of the forks of the epicranial suture, are called 

 fenestrae, and are replaced in the males of some species by 

 ocelli, or simple eyes.. 



The appendages of the head are as follows. The pair of 

 antennae are long and jointed, and in function they are tactile 

 and olfactory. The mouth appendages lie behind the labrum. 

 The mandibles are strong, flattened plates, and each is toothed 

 at the inferior inner border. The first pair of maxillae consist 

 each of a basal protopodite of two segments, termed the cardo 

 and the stipes ; of an endopodite borne by the stipes, the two 



