I] —-CHARACTERS AND STRUCTURE OF THE LEPIDOPTERA. 9 
the framing of their classifications. The various organs of 
the perfect insect are distinctly marked out on the other- 
wise uniform integument of the pupa. In some families, 
notably in the Hepialidae and Micropterygidae, these 
organs are much more distinctly indicated than in others. 
Formerly the term chrysalis was applied to the pupe of 
the Lepidoptera, owing to the fact that many butterfly 
pupe are extensively ornamented with golden-metallic 
markings. (See Plates I, II, and III). 
In common with all other members of the class J nsecta, 
the body of a fully developed Lepidopterous insect consists 
of three main divisions: the head, the thorax, and the 
abdomen. 
The front of the head is termed the face, the top the 
crown, the sides are nearly entirely occupied by the com- 
pound eyes (Plate B., fig. 11, AA), and the lower surface 
by the organs of the mouth. 
The Lyes consist of a very large number of simple 
lenses arranged in the form of two hemispheres, one on 
each side of the head. The ocelli, or simple eyes, are situ- 
ated on the crown, and are usually almost entirely covered 
by seales. 
The Antennae are two jointed appendages attached to 
the top of the head above the eyes. They vary very much 
in structure. The following are the terms used in describ- 
ing the different forms of antenne in the Lepidoptera :— 
1. Pectinated, when the joints have long processes like 
the teeth of a comb. If these are on one side only, the 
antenne are unipectinated; if on both sides, bipectinated. 
(Plate B., fig. 20, bipectinated antenna of Nyctemera 
annulata. ) 
2. Dentate, when the joints are armed with slight 
pointed spines. 
3. Serrate, when the joints have sharp projections like 
the teeth of a saw. (Fig. 18, antenna of Persectania com- 
posita. ) , 
4. Filiform, or setaceous, when the whole antenna is 
simple or thread-like. (Fig. 19, antenna of Epirrhanthis 
alectorari. ) 
The clothing of the antenne also varies, and is dis- 
tinguished 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 sandycias.) 
3. Pubescent, when the antenne are clothed with 
uniform short hairs. (Fig. 19.) 
The functions of the antennz are still a matter of some 
dispute amongst entomologists. The majority of the older 
naturalists regarded them as organs of hearing, but it is 
now considered that an extremely acute sense of smell re- 
sides in the antenne. These organs are almost always more 
fully developed in the male than in the female, and from 
this circumstance it seems that one of their functions is to 
enable the former to find the latter.* 

* See “Butterfly Lore” by Dr. Eltringham, p.p. 112-117. 
The organs of the mouth are thus distinguished :— 
1. The Labrum, or upper lip (Plate B, fig. 11, l), 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. t 
3. The Proboscis, or Haustellumt (c¢), a tubular exten- 
sible organ formed of the two maxillz, 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 maxille. 
The Maxillary palpi are two jointed organs attached 
to the base of the proboscis and very frequently rudi- 
mentary.t t 
The Labiwm, or lower lip, is situated below the pro- 
boscis and earries 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 re- 
moving 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-lke 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 fesmen, 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 is called the apex, and the angle between the termen 
and the dorsum the tornus (see Plate B., fig. 1). The 
termen and dorsum are edged with a fringe of hair-like 
scales, termed the cilia. At the base of the hind-wings is 
generally situated a stiff bristle, or several stiff hairs, called 
the frenulum, the ends of which pass through a chitinous 
process on the under side of the fore-wing near the 
dorsum. This process is termed the retinaculum, and 

+By many modern anatomists these organs are not regarded 
as vestigial mandibles, but rather as lateral lobes of the labrum. 
On this account they are often termed pilifers. 
tThis organ is often termed the tongue. As many mandi- 
bulate insects possess a true tongue, and the proboscis of the 
Lepidoptera is not homologous with the tongue, but with the 
maxillae, I think the term is misleading. 
+7A very interesting article on the Maxillae and Maxillary 
Palpi of the Lepidoptera, by Mr. Philpott, appears in the Tran- 
sactions of the New Zealand Institute, Vol. Lvii, pp. 721-746. 

