The head is in form much like that of certain larvae of Neuroptera and of Forficula, an Orthopterous insect. The basal half of the head is marked off from the eye-bearing piece (epicranium) by a V-shaped suture[10] (Fig. 157, head of Degeeria; compare also the head of the larva of Forficula, Fig. 158, in which the suture is the same), and the insertion of the antennae is removed far down the front, near the mouth, the clypeus being very short; this piece, so large and prominent in the higher insects, is not distinctly separated by suture from the surrounding parts of the head, thus affording one of the best distinctive characters of the Poduridae. The eyes are situated on top of the head just behind the antennae, and are simple, consisting of a group of from five to eight or ten united into a mass in Smynthurus, but separated in the Poduridae (see Fig. 176, _e_, eye of Anurida). The antennae are usually four-jointed, and vary in length in the different genera. [Illustration: 157. Head of Degeeria.] [Illustration: 158. Larva of Forficula.] The mouth-parts are very difficult to make out, but by soaking the insect in potash for twenty-four hours, thus rendering the body transparent, they can be satisfactorily observed. They are constructed on the same general type as the mouth-parts of the Neuroptera, Orthoptera and Coleoptera, and except in being degraded, and with certain parts obsolete, they do not essentially differ.[11] On observing the living Podura, the mouth seems a simple ring, with a minute labrum and groups of hairs and spinules, which the observer, partly by guess-work, can identify as jaws and maxillae, and labium. But in studying the parts rendered transparent, we can identify the different appendages. Figure 159 shows the common Tomocerus plumbeus greatly enlarged (Fig. 160, seen from above), and as the mouth-parts of the whole group of Poduras are remarkably constant, a description of one genus will suffice for all. The labrum, or upper lip, is separated by a deep suture from the clypeus, and is trapezoidal in form. The mandibles and maxillae are long and slender, and buried in the head, with the tips capable of being extended out from the ring surrounding the mouth for a very short distance. The mandibles (_md_, Fig. 159) are like those of the Neuroptera, Orthoptera and Coleoptera in their general form, the tip ending in from three to six teeth (three on one mandible and six on the other), while below, is a rough, denticulated molar surface, where the food seized by the terminal teeth is triturated and prepared to be swallowed. Just behind the mandibles are the maxillae, which are trilobate at the end, as in the three orders of insects above named. The outer lobe, or palpus, is a minute membranous tubercle ending in a hair (Fig. 161, _mp_), while the middle lobe, or galea, is nearly obsolete, though I think I have seen it in Smynthurus, where it forms a lobe on the outside of the lacinia. The lacinia, or inner lobe (Fig.