l6S THE INSECT WORLD. 



The abdomen has the form of an elongated, or — in the majority of 

 species — an ahnost cyHndrical oval. It is composed of five segments, 

 each formed of an upper and a lower ring, joined together by a 

 membrane. The first are larger than the others, and generally 

 overlap the edges, which gives to this part of the body the power of 

 dilating considerably. 



We must dwell longer on the head. It is generally rounded, 

 compressed in front, longer than it is broad, and furnished with fine 

 or scaly hairs. The important organs of which this part is the seat 

 are the eyes, the antennae, the palpi, and the proboscis or trunk. 



The eyes are more or less spherical, surrounded by hairs, and 

 composed of innumerable facettes. Colours are seen on these as 

 various as those of the rainbow. But the colour which serves as 

 a base to all, is black in some, grey in others ; then again there are 

 different gold or bronze colours of the greatest splendour, inclining 

 sometimes to red, sometimes to yellow, sometimes to green. On the 

 compound eye of a butterfly as many as 17,325 facettes have been 

 counted. Simple eyes, or stemmata, are moreover observed in 

 certain species, and are generally more or less hidden by scales. 



The antennae are situated near t*he upper rim or border of each 

 eye. Reaumur has pointed out six principal shapes. One termi- 

 nates in a little knob^ and belongs to the butterflies. The others are 

 variously shaped, and belong to the moths. Some are prismatic, or 

 like beading. And lastly, others are shaped like feathers. We re- 

 present, in Fig. 137, the different forms of the antennae, which 

 Reaumur collected together in plates 8 and 9 of his fifth Memoir.* 



The palpi are four in number, two maxillary and two labial. The 

 first are generally excessively small ; one can only ascertain their 

 existence by the aid of a strong magnifying glass : the second are in 

 general very apparent, straight, cylindrical, covered with scales, and 

 formed of three joints, of which the last is often very small and some- 

 times very pointed. They also sometimes bristle with stiff or silky 

 hairs. 



The trunk is placed exactly between the two eyes. As long as 

 the butterfly does not want to take nourishment, the trunk remains 

 rolled in a spiral. Some are so short, that they scarcely make one 

 turn and a half or two turns ; some larger-sized make three turns 

 and a half or four turns ; lastly, some very long are curled as many 

 as eight or ten times. 



'I'his is how the butterfly makes use of its trunk : when fluttering 



* " Sur les j)ailies exteiieuies cles papilions," tome i., p. 197. 



