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266 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 subulate, and, being placed beneath the eyes, only become visible when the insect is reversed. In the heteropterous 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 immediately with the thorax without any posterior elongation, but numerous examples occur in this order of a distinct neck. Certain species of the Cimicidæ have it so much elongated that the head appears placed upon a narrow peduncle. The prothorax is, for the most part, very much developed, 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 frequently rise from it, rendering the species the most extraordinary looking insects with which we are acquainted. 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,