SmUCTUJiES IMPLICATED IN METAMORPHOSIS. 



23 



pieces are all present, although in a very different condition of 

 form. By removing the fine hairs and scales from the front of the 

 butterfly's head, a small transverse lamina is observable, and its 

 relative position determines it to be the small upper lip, once so 

 large in the caterpillar. On either side and beneath the labrum is 

 a very small piece of skin — the remnant of the once formidable 

 and trenchant mandible. Beneath these is the long trunk, formed 

 by two long and flexible structures, hollow and tubular, and at 

 their base is a pair of small palpi. The flexible tubes are altered 

 inflexible jaws, and the palpi are accessory organs. Below all 



A\ 



MOUTH OP THE PRIVET HAWK MOTH {Sphinx ligustri) Magnified. 

 I. The Larva. 2. The Perfect Insect. 



a. Upper lip. b. Mandibles, c. Jaws. d. Lower lip. e. Antenna. /. Eyes. 



is the inferior labrum, with large palpi attached to it instead of 

 small ones. The suctorial insects, such as the bees and flies, have 

 transformations of the structures of the mouth quite as wonderful 

 as those just mentioned, and they will be noticed further on ; but 

 enough has been said to show what is the nature of the metamor- 

 phosis in these organs. 



The other appendages to the heads of insects are the antennae, 

 commonly called feelers, and the eyes. The eyes are generally 

 developed rather late. Many larvae are blind, and others have 

 immature organs of vision. But in the perfect and adult insects, 

 the eyes are often enormous in size, and most recondite in structure. 

 There are often two kinds of them. Some are very large, and 



