CHAPTER IV 



MOUTH-PARTS, WINGS, AND LEGS 



Let us imagine for a moment that we are looking into 

 the face of a cockroach. The smooth, rounded forehead, 

 the large eyes, and the bases of the antennas are all pro- 

 minent features ; but the mouth — i.e. the opening which 

 leads to the gullet — is hidden by a hard plate which is 

 hinged to the solid armour of the head. This is the upper 

 lip, or labrum. Behind it are the three pairs of mouth- 

 parts which were derived from the primitive foot-jaws. 

 First come the mandibles, which play the chief part in 

 tearing and biting food. Then another pair of jaws, called 

 maocillce, less powerful than the mandibles, but highly 

 sensitive. Each maxilla is made up of four segments. 

 There is a small basal piece, the cardo, attached to the 

 framework of the head. To this a larger vertical piece, 

 the stipes, is jointed. It carries a feeler, or palpus ; also, 

 at its lower extremity, the lacinia or blade — the cutting 

 tool of the maxilla, as it were — with its sheath, or galea. 

 The maxillas, indeed, are well equipped for examining 

 food, holding it, and passing suitable fragments towards 

 the gullet. In the case of most biting insects, they act 

 like a pair of dexterous hands set just under the mouth. 

 Moreover, they are backed by a smaller pair of similarly 

 jointed jaws, called the second maxillas, which are also 

 furnished with palpi. The basal segments of this third 

 and last pair of jaws are fused together so as to form one 

 plate-like structure; thus the second maxillse are often 

 spoken of by naturalists as if they were a single organ, 



