STRUCTURE OF INSECTS. 9 



Fabricius): this is followed by a generally membranous organ (labium 

 or the ligula of Fabricius), near to the external base of which is 

 attached a pair of short articulated palpi ; within this terminal la- 

 bium is to be seen a fleshy organ, often forming its internal coating, 

 but which in the dragon-fly and the grasshopper is a separate piece 

 (lingua), and of which the lateral anterior angles (paraglossce) are oc- 

 casionally prominent. Such is the general character of the mouth of 

 the Coleoptera, Orthoptera, Neuroptera, and Hymenoptera. In the 

 bees, however, the three inferior organs of the mouth are elongated, 

 so as when in action conjointly to form a sucking apparatus ; the 

 mandibles, however, retain their ordinary form. Latreille, notwith- 

 standing, terms this form of mouth Promuscis, a term long previously 

 given by Kirby and Spence to the mouth of the Hemiptera. 



Amongst the Suctorial Insects, there is a much greater diversity of 

 structure in the mouth. In the Hemiptera and Homoptera, the 

 upper organ is very short and pointed ; the four lateral pieces are 

 elongated and transformed into slender lancet-like organs (the max- 

 illary palpi being obsolete), enclosed within the equally elongated 

 fleshy and articulated lower lip, which is turned upwards at the sides, 

 forming a canal, up which the fluid food of the insect ascends ; the 

 labial palpi are also here obsolete. This variation of the mouth is 

 termed by Kirby and Spence, promuscis ; but by Fabricius, Olivier, 

 and Latreille, rostrum. In tlie Diptera, the five upper organs, to- 

 gether also with the internal tongue, are elongated into lancet-like 

 organs, the maxillary palpi being attached at the base of the maxillae. 

 These six organs are inclosed in a fleshy thickened piece (which is the 

 lower lip), terminated by two large fleshy lobes which act as suckers. 

 In many species, however, s.ome of these lancet-like organs are obsolete. 

 This kind of mouth is termed by Kirby and Spence, Linnaeus and 

 Fabricius, a proboscis. In the Lepidoptcra, the three upper organs 

 are almost obsolete, but the maxillae are greatly elongated into a 

 delicate instrument, which when at rest is spirally folded up and 

 hidden from sight, but when in action, is extended and thrust to the 

 bottoms of flowers. At the base of these maxillae, a pair of minute 

 palpi is often to be found. The lower lip is soldered to the head, but 

 it is furnished with a pair of large palpi clothed with scales, which 

 serves for the defence of the spiral maxilkc. By Kirby and Spence, 

 this kind of mouth is termed antlia; by Fabricius, lingua ; and by 

 Latreille, spirignatha (or more properly spcirignatha). In the Apha- 



