INTRODUCTION. m 



3. Serrate, when the joints have sharp projections like the teeth of a saw. (Fig. is, 

 antenna of Melanchra composita.) 



4. Filiform, when the whole antenna is simple or thread-like. (Fig. 1!), antenna of 

 Epirranthis alectoraria.) 



The clothing of the antenna' also varies, and is distinguished as under: 



1. Ciliated, when clothed with one or two series of short, fine hairs. 



•1. Fasciculate-ciliated, when the hairs are collected into tufts. (Fig. 17, antenna of 



Cllloroclljstis idinthilUl.) 



3. Pubescent, when the antenna- are clothed with uniform short hairs. (Fig. 19.) 



The functions of the antenna' are still a matter of dispute amongst entomologists. 

 The majority of the older naturalists regarded them as organs of hearing. The antenna' 

 are almost always more fully developed in the male than in the female. From this 

 circumstance many modern entomologists consider that one of their functions is to enable 

 the former to find the latter. 



The organs of the mouth are thus distinguished : — 



1. The Labrum, or upper lip (Plate 1., fig. 11, I), a minute rudimentary plate 

 situated in front immediately above the proboscis. 



•J. The Mandibles, or upper jaws (m.m), two minute sickle-shaped organs situated 

 just below the labrum, also rudimentary. 



:',. The Proboscis, or Haustellum (c), a tubular extensible organ formed of the 

 two maxilla 1 , or lower jaws, which have become greatly elongated, semi-tubular, and closely 

 pressed together al the edges, but separable at the will of the insect -a structure which 

 enables the organ to be easily cleansed when necessary, and is extremely interesting as 

 indicating so clearly the true development of the proboscis from the maxilla'. 



The Ma.rillaru palpi (p.p) are two jointed organs attached to the base of the 

 proboscis and very frequently rudimentary, but fully developed amongst certain of the 

 Micro-Lepidoptera. 



The Labium, or lower lip, is situated below the proboscis and carries the Labial palpi 



(figs. •") and 6), two large jointed organs which are very conspicuous in nearly all the 



species and often quite conceal the maxillary palpi. They are usually regarded as organs of 



touch, but their true function does not seem to be properly understood. In the Lepidoptera 



they appear to protect the proboscis, which, when out of use, is always coiled up in a spiral 



between them. The labrum and mandibles can only be seen by removing the large labial 



palpi. 



THE THORAX 



carries the organs of locomotion, which consist of two pairs of wings attached to its 



sides, and three pairs of legs attached beneath, a pair belonging to each of the three 



segments of which the thorax is composed. On the front of the thorax there are two 



flap-like organs covered with scales, termed the patagia. 



The Wings vary greatly in shape, but usually they are triangular. The portion of the 



wing which joins on to the thorax is termed the base. The front margin is called the 



costa, the outer margin the termen, and the lower margin the dorsum, these being described 



as situated when the wing is extended in flight. The angle between the costa and termen 



* This organ is termed the tongue by Mr. Meyrick. As many mandibulate insects possess a true tongue, and 

 the proboscis of the Lepidoptera is not homologous with the tongue, but with the maxilla'. I think the term is very 

 misleading. 



