Turning to Plate VII. Fig. [4], we find the head of a ground beetle (Cárabus), valuable as exhibiting the whole of the organs of the head and mouth.
Immediately above the compound eyes are seen the roots of the antennæ, those organs themselves being cut away. Above there are two pairs of similarly constructed organs termed the “maxillary palpi,” because they belong to the lesser jaws or maxillæ, seen just within the pair of great curved jaws called the mandibles, which are extended in so threatening a manner. The “labial palpi,” so called because they belong to the “labium,” or under lip, are seen just within the others; the tongue is seen between the maxillæ, and the chin or “mentum” forms a defence for the base of the maxillæ and the palpi. A careful examination of a beetle’s mouth with the aid of a pocket lens is very instructive as well as interesting.
Fig. [1] on the same Plate shows the jaws of the hive bee, where the same organs are seen modified into many curious shapes. In the centre may be seen the tongue, elongated into a flexible and hair-covered instrument, used for licking the honey from the interior of flowers. At each side of the tongue are the labial palpi, having their outermost joints very small, and the others extremely large, the latter acting as a kind of sheath for the tongue. Outside the labial palpi are the maxillæ, separated in the specimen, but capable of being laid closely upon each other, and outside all are the mandibles.
VI.
| FIG. | |||
| 1. | Antenna, Cricket | 16. | Do. do. section |
| 2. | Do. Grasshopper | 17. | Do. Ichneumon |
| 3. | Do. Staphylinus | 18. | Eye of Butterfly, Atalanta |
| 4. | Do. Cassida | 19. | Eyes, Bee |
| 5. | Do. Staphylinus | 20. | Eye, Death’s Head Moth |
| 6. | Do. Weevil | 21. | Breathing-tube, Silkworm |
| 7. | Do. Pyrochroa | 22. | Eye, Heliophilus |
| 8. | Do. Butterfly, Tortoiseshell | 23. | Do. Lobster |
| 9. | Do. Gnat, male | 24. | Do. Aphis of Geranium |
| 10. | Do. Syrphus | 25. | Head, Parasite of Tortoise |
| 11. | Do. Cockchafer, male | 26. | Hind leg, Aphis of Geranium |
| 12. | Do. Ground Beetle | 27. | Head, Gnat |
| 13. | Do. Ermine Moth | 28. | “Paps” of Aphis |
| 14. | Do. Tiger Moth | 29. | Head, Sheep-tick |
| 15. | Do. Blowfly | 30. | Foot, Tipula |
VI.
The curiously elongated head of the scorpion-fly (Panorpa), seen at Fig. [7], affords another example of the remarkable manner in which these organs are developed in different insects. Another elongated head, belonging to the daddy long-legs, is seen in Plate VI. Fig. [27], and well shows the compound eyes, the antennæ, and the palpi. Fig. [2] represents the coiled tongue of the Atalanta butterfly; it is composed of the maxillæ, very greatly developed, and appearing as if each had originally been flat, and then rolled up so as to make about three-fourths of a tube. A number of projections are seen towards the tip, and one of these little bodies is shown on a larger scale at Fig. [3]. These curious organs have probably some connection with the sense of taste. Along the edges of the semi-tubes are arranged a number of very tiny hooks, by means of which the insect can unite the edges at will.