LEPIDOPTERA : STRUCTURE. 391 



is destitute of any sting, although Dr. Burmeister has 

 recently noticed an exotic species contained in the Royal 

 Collection at Berlin, which appeared to be provided with an 

 instrument of this kind, but which I should be inclined 

 rather to regard as the acute extremity of the ovipositor, 

 which, in many of the species whose larvae are subterraneous 

 or subcortical in their habits, is long and acute. The body 

 of these insects is very pilose ; it is also very variable in 

 respect to its size ; those species which are pre-eminently 

 distinguished for their powers of flight having the body, and 

 especially the thorax, very robust ; whilst in the Erycinidae, 

 Geometridce, and many others whose flight is weak, it is 

 slender; indeed the last-mentioned family has, from this 

 circumstance, obtained the name of slender-bodies amongst 

 the English collectors. The form of the pterygodes also is very 

 variable, giving to the thorax a diversity of appearance ; thus 

 in the genus Cucullia (moths belonging to the family 

 Noctuidee) the pterygodes are very large, and the thorax is 

 pushed forwards, forming a sort of hood over the heads, 

 whilst in Xylina they are more elongated, so as to give the 

 sides of the thorax an elevated appearance, with the centre 

 depressed. The colour of the thorax is generally similar to 

 that of the anterior wings in the majority of the moths, as 

 well as in the butterflies, in which it is clothed with fine hairs ; 

 but the prothorax often presents peculiarities of character : 

 thus, in the larger typical butterflies, Papilionidte, it is 

 marked with two or more red or yellow spots, sometimes 

 uniting to form a kind of collar. The wings are attached to 

 the lateral and superior part of the thorax, and are always 

 present, except in a few species of which the females are 

 apterous, or have the wings reduced to small and useless 

 appendages : the fine layers of membrane of which the^wings 

 are composed, like the upper and lower surface of a leaf, are 

 kept expanded by a number of longitudinal corneous veins 



