INTRODUCTION 



The proboscis, or tongue, is an extensible tubular organ, 

 fitted for sucking up the nectar of flowers, and usually spirally 

 coiled when not in use ; it is composed of the maxillae, which 

 are semitubular and closely appressed together at the edges, but 

 separable at the will of the insect ; this arrangement enables the 

 apparatus to be cleansed internally. Although it is usually 

 the only means of taking food, it is in some species absent or 

 so rudimentary as to be useless. 



The mandibles are biting jaws, working against one another 

 sideways; they have only been observed in a functionally 

 active condition in Eriocephala, being apparently aborted or 

 rudimentary in all other imagos, though necessarily well 

 developed in the larvae. 



The maxillary palpi are jointed organs rising from the base 

 of the maxillae ; when fully developed they are six-jointed and 

 usually more or less folded on themselves, but in the large 

 majority of species they are reduced to mere rudiments, 

 their functions being probably assumed by the labial palpi. 

 In certain groups they occur in an intermediate three-jointed 

 stage, somewhat resembling the labial palpi, but on a much 

 smaller scale. 



The labial palpi are normally three -jointed organs, rising 

 from the labium or lower lip, and projecting outside the 

 maxillary palpi. The basal joint is generally small and incon- 

 spicuous, but the other two in some groups vary greatly in 

 size, form, and scaling. They may be straight or curved ; 

 drooping, porrected, or ascending ; smooth, rough, or tufted ; 

 obtuse or pointed. The palpi are usually regarded as organs 

 of touch, but no explanation of their variety of form has been 

 suggested ; they are independently movable, but in the case 

 of the Lepidoptera it does not seem that their use is really 

 understood. 



The thorax varies little except in scaling, and the presence 

 or absence of dorsal crests. Covering the shoulders are two 

 chitinous scaled flaps, termed the patagia. 



The abdomen is sometimes also furnished with dorsal crests. 

 At its base are two lateral cavities, more or less developed, 

 which appear to be the organs of some sense. The abdomen 

 terminates in a tuft of scales covering the orifice, the anal 

 tuft. Within the orifice are concealed the genital organs, 

 which are capable of protrusion ; and also the ovipositor of 

 the female, though this is in many cases permanently 

 exposed. The genital organs of the male differ greatly in 



