The head is always conspicuous, composed of horny or chitinous material, but varying exceedingly in form and size. It is very rarely small and retracted. It is generally large, hemispherical, conical, or bilobed. In some families it is ornamented by horn-like projections. On the lower side are the mouth-parts, consisting of the upper lip, the mandibles, the antennæ, or feelers, the under lip, the maxillæ, and two sets of palpi, known as the maxillary and the labial palpi. In many genera the labium, or under lip, is provided with a short, horny projection known as the spinneret, through which the silk secreted by the caterpillar is passed. On either side, just above the mandibles, are located the eyes, or ocelli, which in the caterpillar are simple, round, shining prominences, generally only to be clearly distinguished by the aid of a magnifying-glass. These ocelli are frequently arranged in series on each side. The palpi are organs of touch connected with the maxillæ and the labium, or under lip, and are used in the process of feeding, and also when the caterpillar is crawling about from place to place. The larva appears to guide itself in great part by means of the palpi. +--------------------------------------------------------------+ | | | EXPLANATION OF PLATE II | | | | Reproduced, with the kind permission of Dr. S.H. Scudder, | | from "The Butterflies of New England," vol. iii, Plate 76. | | | | | | | | CATERPILLARS OF PAPILIONIDÆ AND HESPERIIDÆ | | | | 1. _Colias eurytheme._ | | 2. _Callidryas eubule._ | | 3. _Terias lisa._ | | 4. _Callidryas eubule._ | | 5. _Euchloë genutia._ | | 6. _Terias nicippe._ | | 7. _Pieris protodice._ | | 8. _Pieris napi_, var. _oleracea_. | | 9. _Pieris napi_, var. _oleracea_. | | 10. _Colias philodice._ | | 11. _Pieris rapæ._ | | 12. _Pieris rapæ._ | | 13. _Papilio philenor._ | | 14. _Papilio ajax._ | | 15. _Papilio turnus._ Just before pupation. | | 16.