ANNULOSA. 533 



The labrum is analogous to the upper lip of the higher 

 classes of animals. It is articulated to the fore part of the 

 head {fronSy or clypeus, chaperon of the French), either 

 direcdy by a simple suture, or by the intervention of a 

 plate, to which Mr Kirby, from its situation, has given 

 the name nasus. The labrum itself, at its free edge, ex- 

 hibits great variety of character in the condition of its mar- 

 gin, of which naturalists have availed themselves in the 

 discrimination of species. This organ may be regarded as 

 the cover to the other parts of the mouth above. 



The mandibulee are two in number. They take their 

 rise immediately below the labrum on each side. They 

 exhibit very remarkable differences in size, shape, and ar- 

 mature. They move horizontally, and serve to cut objects 

 by dieir edges crossing like the blades of scissars. 



The maxilloe are likewise two in number. They are 

 united to the cheeks immediately underneath the mandi- 

 bulae, and between these organs and the labium. They 

 are more complicated than the mandibulae. On their inner 

 margin, they are usually covered with stiff hairs. Exter- 

 nally they support the palpi, which are articulated ap- 

 pendages, consisting of two or more joints. Each maxilla 

 is furnished with one of these, rarely with two. The "use 

 of the palpi has not been determined, although it is pro- 

 bable that they serve as organs of smell, and perhaps also 

 of touch. 



The labium is analogous to the under lip, and closes the 

 under side of the mouth, pressing the maxillae. Its free 

 edge is variously marked, and there is usually a line in the 

 middle indicating its tendency to be double. On each side 

 it supports a palpus, consisting of two or three joints. Its 

 base is connected, laterally, by ligament, with the base of 

 the maxillae, and behind, with a fixed plate jointed to the 



