12 
MEMBRA CIDJE. 
generally ends in a sharp black point. It may be curved downwards as in Ceresa, 
or straightly prolonged as in Polyglypta. It may be twisted as in Ophiocentrus, 
or expanded into a sub-triangular flattened blade, like a ship’s rudder, as in 
Pedal ion. 
Briefly it miglit be almost thought that through some convulsive action, these 
insects had been permanently fixed in catalepsy, and had thus perpetuated their species 
in the form of a menace to their enemies. 
The pronotum, as before noted, is the most highly developed part of the thorax in 
the Membracidse, but although so superior in size its uses as thus expanded can only 
be the subject of conjecture. In Heteronotus the globular masses are very large and 
filled with air, so most probably they are connected with the respiratory system. 
They may be looked upon as analogous to the remarkable head-developments of the 
lantern flies, Laternaria, and the snouts of Pyrops. From such examples as I have 
examined after maceration in water, I have not been able to detect distinct tracheae 
on the inner walls of these hollow balls, though there is an indication of such 
vessels. The proofs of their presence and import can only come from dissection of 
recent or living forms. The laminated pronotum of Membracis proper is easily seen 
to consist of two layers or sheets of chitin, united at their outer edges, and widening 
below as a cavity to embrace the body above the dorsum of the insect. 
The pronotum is almost always pitted by shallow depressions or punctures. These 
do not seem to be perforations, but they permit the light to pass through them as 
bright dots when suitably placed on the microscope stage. 
As a shell this part of the thorax may be sufficiently large to cover the whole of 
the tegmina. Generally the head and the eyes are also so wholly covered by it, that 
they cannot be seen from above. 
Much may be learnt by the use of a lens directed towards the front of the insect, 
in which position numerous outline drawings have been made, to represent the head 
with the procephalic processes and the supra-humeral horns. The contour of these 
parts is of much assistance in deciding on the genus and species of an insect. 
The whole of the above complex development of the pronotum is practically 
united into a single piece, which can be easily detached from the head and body 
of the dry insect, the point of articulation being marked on the mesothorax beneath 
by a sort of crescentic articulation above the great lobes which operate as attachments 
for the muscles of the tegmina and wings. The pronotum has often a kind of septum 
near the posterior end, which completes the enclosing walls of these curious air-chambers. 
The Mesonotum and the Metanotum , so obvious in other insects, are in the 
Membracidse concealed, but their presence may be easily shown by removal of the 
sheath of the pronotum. 
