The following table is designed to show the number and succession of the segments of the head, with their respective segments.
TABULAR VIEW OF THE SEGMENTS, PIECES (SCLERITES), AND APPENDAGES OF THE HEAD
═══════════════════════════════╤═══════════════════╤═══════════════════ NAME OF SEGMENT │ PIECES OR REGIONS │ APPENDAGES, ETC. │OF THE HEAD-CAPSULE│ ───────────┬───────────────────┼───────────────────┼─────────────────── │1. Ocellar │Epicranium, │Compound and simple _Preoral_, │ (Protocerebral). │ anterior region │ eyes (Ocelli). in early │ │ with the clypeus │ embryo. │ │ labrum, and │ │ │ epipharynx. │ │ │ │ _Postoral_,│2. Antennal │Epicranium, │Antennæ. in early │ (Deutocerebral). │ including the │ embryo. │ │ antennal sockets.│ │ │ │ │3. Premandibular, │Wanting in │Premandibular │ or intercalary │ postembryonic │ appendages (in │ (Tritocerebral). │ life, except in │ Campodea). │ │ Campodea. │ │ │ │ │4. Mandibular. │Epicranium behind │Mandibles. │ │ the antennæ, │ │ │ genæ. │ │ │ │ │5. 1st Maxillary. │Epicranium, hinder │1st Maxillæ. │ │ edge? Tentorium. │ │ │ │ │6. 2d Maxillary, or│Occiput. │2d Maxillæ or │ labial. │ │ Labium. │ │ │ Post-gula, gula, │ │ │ submentum, │ │ │ mentum, │ │ │ hypopharynx │ │ │ (lingua, ligula), │ │ │ paraglossæ, │ │ │ spinneret. ───────────┴───────────────────┴───────────────────┴───────────────────
FIG. 38.—Larva (_a_) of a chalcid, about to pupate, with the head, including the eyes and three ocelli, in the prothoracic segment: _b_, _c_, pupa. ]
=The composition of the head in the Hymenoptera.=—Ratzeburg stated in 1832 that the head in the adult Hymenoptera (Cynips, Hemiteles, and Formica) does not correspond to that of the larva, but is derived from the head and the first thoracic segment of the larva. Westwood and also Goureau made less complete but similar observations, though Westwood afterwards changed his opinion, and the same view was maintained by Reinhard. Our own observations (as seen in Fig. 38) led us to suppose that this was a mistaken view; that the larval head, being too small to contain that of the semipupa, was simply pushed forward, as in caterpillars. Bugnion, however, reaffirms it in such a detailed way that we reproduce his account. He maintains that the views of Ratzeburg are exact and easy to verify in the chalcid genus Encyrtus, except, however, that which concerns the ventral part and the posterior border of the prothoracic segment.