54 INSECT TRANSFORMATION 



the jaws. Unless they be possibly represented by a pair of 

 tiny pointed lobes (Fig. 31 A, m) attached to the upper lip, 

 mandibles are altogether wanting. The maxillae, on the other 

 hand, are most highly specialized for sucking liquid food, 

 their outer lobes (or galeae) (Fig. 31 A, g) being drawn out 

 into long flexible structures, grooved on their inner faces so 

 that when applied to one another and fastened by a suitably 

 arranged set of interlocking bristles, they form a tubular trunk 

 which can be stretched out so as to gather nectar from plant- 

 blossoms, or coiled up somewhat in the manner of a watch 

 spring beneath the head. On the outer edge of the base 

 (Fig. 31 B b) whence this galea springs is borne a palp (p), 

 which in butterflies and the vast majority of moths is a mere 

 vestige a slender process with a terminal knob and a tuft of 

 scales but which in some families of small moths is developed 

 in the typical jointed form. No trace of the inner maxillary 

 lobe (lacinia] can be detected except in a single family of very 

 small insects which stand at a markedly lower stage of 

 specialization than typical moths and butterflies. The labium 

 is also highly modified, with the suppression of some of its 

 parts ; it consists of a transverse narrow plate beneath the 

 maxillae, bearing a pair of rather conspicuous, upturned, 

 scaly palps (Fig. 31 A, p), but with the typical paired lobes 

 (galeae and laciniae) represented only by a small median 

 process. 



The butterfly's thorax is more compact that the grass- 

 hopper's with the segmentation less evident. The prothorax 

 is less prominent ; being covered with scales its form is not 

 readily appreciated by cursory observation, but a pair of 

 erectile scaled plates (the patagia) on the dorsal aspect are 

 noteworthy. The mesothorax has also a pair of dorsal scaled 

 plates (the tegulae), which overlie the bases of the fore wings. 

 The wings, with their usually close clothing of scales, arranged 

 often so as to produce a coloured pattern of brilliance and 

 beauty, are a dominating feature of the insect. The forewing 

 is longer than wide, sub-triangular in shape, and relatively 

 stiff in texture, while the hindwing, shorter and usually broader, 

 may have the region occupied by the anal nervures capable 

 of slight folding. The nervuration (Fig. 35) is predominantly 

 longitudinal, the cross-nervules so abundant on the wing of 



