OF THE ANNULOSA. 359 



called neuters being only abortive females. Rare instances 

 of hermaphroditism indeed occur, but are invariably to be 

 accounted as monstrous, and as contrary to the ordinary 

 course of nature as the same imperfection when visible 

 among the l^ertebrata. 



The mouth of W inged insects is composed of six prin- 

 cipal pieces, of which four, called the mandibulee and maxil- 

 lee, move transversely in pairs, while the remaining two are 

 fixed, and close the mouth vertically. The two maxillas 

 and the lowest of the vertical pieces are in general all sup- 

 plied with articulated processes, of various shapes, called 

 Palpi. Such is the comprehensive view which the inge- 

 nious Savigny first enabled us to take of the mouths of 

 insects. On examining these animals more closely, it will, 

 however, be noticed that they form two principal classes, 

 since in some orders the four lateral pieces above men- 

 tioned, or at least two of them, take the form of teeth, 

 and the two vertical pieces that of lips : in other insects, 

 again, the lateral pieces never serve as teeth, and all the 

 six component parts of the mouth, or certain of them, be- 

 come elongated so as to constitute a rostrum. The first 

 group must necessarily chew or lick their food ; where- 

 as the latter suck theirs, or more properly the fluids of 

 which it is composed seem to mount into the oesophagus of 

 the insect by a kind of capillary attraction. 



The distinction which exists between these classes was 

 originally detected by Aristotle*. M . Cuvier among the 

 moderns was the first to perceive them to be natural ; but he 

 was not then sufficiently acquainted with the subject to cha- 

 racterize either of them accurately, as the works of Savigny 



