INTRODUCTION. xi 



3. Serrate, when the joints have sharp projections like the teeth of a saw. (Fig. 18, 

 antenna of Mehinclira composita.) 



4. Filiform, when the whole antenna is simple or thread-like. (Fig. 19, antenna of 

 Epirrantlns alectoraria.) 



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



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



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

 Chloroclystis plintli /ma.) 



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

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



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

 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 I., fig. 11, /), a minute rudimentary plate 

 situated in front immediately above the proboscis. 



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

 just below the labrum, also rudimentary. 



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

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

 pressed together at 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 maxillae. 



The Maxillary 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. 5 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 THOEAX 



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 tennen, and the lower margin the dor sum, 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. Meyriok. As many mandibulate insects possess a true tongue, and 

 the proboscis of the Lepidopiera is not homologous with the tongue, but with the maxillae, I think the term is very 

 misleading. 



