266 SYSTEMATIC ARRANGEMENT. 



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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 Cimicidse 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, 



