76 INTRODUCTION. 



received from the commander of the vessel during 

 the voyage, I enjoy the satisfaction of having brought 

 the whole in safety to England*." 



The systematic arrangement of this tribe of in- 

 sects has always been considered a task of great 

 difficulty. So convinced of this was Latreille, who 

 had himself studied the subject profoundly, that he 

 says a classification of lepidoptera may be considered 

 the touchstone of entomologists. This difficulty 

 arises chiefly from the uniformity of organization 

 which prevails throughout the order — a uniformity 

 occasioned by all of them being designed to subsist 

 on liquid food, and to imbibe it in the same man- 

 ner. The oral organs, therefore, which are of the 

 first importance in classifying other tribes — the cole- 

 optera, for example, in which they undergo almost 

 endless variations of form and consistency to fit 

 them for consuming every kind of organic substance, 

 from semi-fluid animal or vegetable matter to the 

 hardest ligneous tissue— are, in this instance, of 

 comparatively little avail. Recourse must be had 

 to secondary and subordinate characters ; and even 

 when we are convinced that, owing to a peculiar 

 facies, and the concurrence of many minute resem- 

 blances, certain groups should be regarded as dis- 

 tinct, it is found difficult to define them in a satis- 

 factory manner. Neither has the difficulty been 

 much lessened by the manner in which the subject 



* Horsfiel<Ts Catal. of the Lepidopterous Insects of Java, 

 Intro, p. 9. 



