THE COMMON COCKROACH 129 



freely movable three-jointed appendages beset with hairs 

 (labial palpi). We shall recur to the structure of the 

 labium presently ; meanwhile we may pass to the next 

 part of the feeding apparatus. This consists of a pair of 

 jointed organs (maxillae), one on each side, clearly revealed 

 by the removal of the labium. One of these may be 

 removed (Fig. 38) and examined in the same way as 

 the labium. It is seen to consist 

 of two basal joints, the cardo and 

 the stipes, followed by a blade- 

 like piece attached to the end of 

 the stipes, and divided longi- 

 tudinally into two parts, the 

 inner (lacinia), hard, blade- 

 shaped, arid beset with stiff 

 bristles along its inner edge, and 

 the outer (galea) less hard, and 

 receiving the tip of the lacinia 

 in a groove in itself. Outside 

 this second segment of the jaw, Fjo _ 3 ' 8 _ Maxilla of Cockroach . 



and also attached to the stipes, c \ c ard ; s > stipes; z, la- 



cinia ; g, galea ; p, palpus, 

 is a freely movable five-jointed 



organ, the maxillary palpus, set with hairs. 



From this description, taken in conjunction with the 

 figure, it is evident that the structure of a single maxilla 

 is very much like that of each half of the labium ; 

 indeed, if we were to imagine the cardo and stipes of 

 each maxilla considerably broadened, and then those of 

 the opposite sides united by their inner edges, we should 

 get an organ on a somewhat larger scale, indeed, but 

 otherwise almost the exact counterpart of the labium. 

 And such, in fact, is the composition of this complex 

 organ, the labium ; it consists, namely, of a pair of jaws 

 (second maxillae) fused together by their basal portions, 



