The Antennæ are formed of various shapes, according to the different genera, as may be observed in the figures, and seem instituted by nature not only for guiding the animal in its passage, but likewise for other purposes; being endued with an exquisite sense of feeling and perception. Fig. 1. d d. Fig. 2. c. Fig. 3. c c.
The Mouth is placed in the head, but sometimes close to the breast, as in the spider tribe; sometimes terminating in a horny beak, as in Plate [32]. Fig. 1. also in Plate [42]. Fig. 3 and 7. In some it is furnished with strong mandibles like pincers, as in Plate [32]. Fig. 6. and Plate [37]. Fig. 1, 2, 3, 4, 5, 6. In others it is so covered and guarded by the palpi, particularly among the moths, that it is not to be seen.
The Palpi are parts placed close to the mouth, and variously shaped; as may be seen by comparing those of the Lepidopterous with those of the Coleopterous, and other tribes; consisting of a greater or less number according to the species or genus; in some being only two, in most of them four, and in some six, (Cicindela, Carabus, Linn.) The use and purpose of these parts we are ignorant of. Fig. 1. c c. Fig. 2. b. Fig. 3. b b.
The Eyes are generally immoveable, and suited differently; in some to see only in the night, in others in the day; and differ in number according to the genera and species, having in general two only, but in some five,[[18]] in others eight, as the spiders. Fig. 1. b b. Fig. 3. d d.
The Tongue (elongated maxillæ) is sometimes curled up spirally like the spring of a watch, as in butterflies and some moths, &c. in others it (including the labium) is doubled under the head, as in bees and wasps; but a great many species are destitute of this elongated part.
The Thorax is principally composed of the BACK, BREAST, and in some the SCUTELLUM, in others the MESOSTERNUM and DILATED POSTERIOR COXÆ.
The Back, dorsum or upper part, answering to the back in some animals, terminates in some species in a triangular manner, so as to represent the scutellum, as in Plate [33]. Fig. 5, 6, and 8. Tab. Ann. Fig. 1. f. Fig. 2. e.
The Breast, or sternum, is the under part of the thorax, and always furnished with legs.
The Scutellum is a small but hard part like a scale, frequently of a triangular shape, placed behind the dorsum of the prothorax, and joining to it. It is not developed in every genus, being chiefly perceived in the Coleopterous, Hemipterous, and transparent-winged orders.
The Mesosternum is united to the fore part of the breast, extending beyond the middle legs towards the fore ones; and observable only in some species of the Coleopterous order. By Linnæus and several other authors it is called sternum.