25 
The Wings are each composed of an upper and lower trans- 
parent membrane, and between these, tlie blood vessels and 
respiratory tubes spread out so as to form a comparatively strong 
network for the support of the extended membranes. The wings 
are attached to the thorax by very strong muscles and they are 
capable of making as many as four thousand strokes per second. 
The Halteres are little stalks immediately behind the wings, 
having a globular expansion at the ends, and are probably 
rudimentary wings. 
The Respiratory apparatus, consists of spiracles and trachex. 
The spiracles are on the underside of the body, and are 
really small holes or pores, filled with a spongy fibre which 
allows the air to filter in, while at the same time cleansing it 
from all impurities. The trachee are small tubes strengthened 
with spiral fibre coiled round the inside: they are connected 
with the spiracles, and ramify to all parts of the body. 
The Leg consists of five distinct jomts, giving the limb free 
movement in any direction. The legs of insects are possessed 
of great power, for instance, while a man can drag about his 
own weight, the fly can drag thirty times hers. 
The Foot consists of two movable claws which are used to 
clean out moats, dirt, &c., which have become entangled in the 
spiracles; also of two membraneous expansions or pads which 
probably serve to protect the claws and keep them from being 
roughened or broken. Around the margin, and on the surface of 
the pads are innumerable glandular hairs from which a fluid is 
exuded. These probably act as “‘ suckers” and enable the fly to 
walk up perpendicular and smooth surfaces. 
The Tongue is a very beautiful and complicated structure, 
and consists of three lancets to puncture substances and cause 
the juices to flow. Then comes the tongue proper, which is an 
expansion of membrane containing many cross channels or half 
tubes. These all empty themselves into two larger grooves 
which join together and run into the eullet. 
The Antenne are like two little horns protruding from the 
front part of the head. They consist of apparently three, but 
really six joints, of which the third is dilated, and much larger 
than the rest. At its base are three or four cavities closed from 
the outer air by a delicate skin, while from their lower surface a 
nerve proceeds to the brain. These are probably organs of hear- 
ing or smell, for by their means insects communicate with each 
other, and receive most of their impressions of the outer world. 
The yes are five in number, three having a simple undivided 
surface or cornea; two larger ones having a cornea divided into 
hexagonal facets, four thousand in number. The more minute 
structure of the eyes is very interesting but cannot be described 
in detail in this short abstract. 
The lecture was illustrated by a number of large drawings 
which had been prepared by Mr. Rhodes. 
