266 
SYSTEMATIC ARRANGEMENT. 
terous tribes they are usually very inconspicuous, 
sometimes so small as almost, on a general view, to 
escape observation. This is the case with Fulgora, 
Nepa, Ranatra, &c. in which they are short and sub- 
ulate, and, being placed beneath the eyes, only become 
visible when the insect is reversed. In the heterop- 
terous section, however, they are often of considerable 
length, and, in not a few instances, some of the joints 
are suddenly and broadly dilated. The articulations 
vary in number from two to eleven. 
In the majority of insects the head articulates im- 
mediately with the thorax without any posterior elong- 
ation, but numerous examples occur in this order of 
a distinct neck. Certain species of the Cimicidee have 
it so much elongated that the head appears placed upon 
a narrow peduncle. 
The prothorax is, for the most part, very much de- 
veloped, but a gradual diminution can be traced among 
the genera till it become a mere collar. It reaches 
its maximum among the heteroptera, and is usually 
much contracted among the homoptera. It is chiefly 
remarkable for the singular projections which fre- 
quently rise from it, rendering the species the most 
extraordinary looking insects with which we are ac- 
quainted. It is very often produced laterally into 
two long spines, which are sometimes truncated, at 
other times pointed, sometimes directed forwards, at 
other times curved backwards. Instead of spines, 
these projections occasionally assume the form of 
foliaceous appendages, notched or serrated on the 
edges. In Ledra they have the appearance of ears. 
