I.
Ontogeny and Morphology of Sphinx-Markings.
THE GENUS CHÆROCAMPA, DUPONCHEL.
Although by no means in favour of the excessive subdivision of genera, I am of opinion that Ochsenheimer’s genus Deilephila has been correctly separated by Duponchel into the two genera Chærocampa and Deilephila, sensû strictiori. Such a division may appear but little necessary if we examine the perfect insects only; but the developmental history of the caterpillars shows that there is a wide division between the two groups of species, these groups however being branches of one stem.
Chærocampa Elpenor, Linn.
Some captured females laid single eggs sparsely on grass, wood, and especially on the tarlatan with which the breeding-cage was covered. The eggs are nearly spherical, but somewhat compressed, of a grass-green colour, a little lighter, and somewhat larger (1.2 millim.) than those of Deilephila Euphorbiæ. During the development of the embryo the eggs first became yellowish-green, and finally yellowish.
First Stage.
The young caterpillars are four millimeters in length, and immediately after hatching are not green, but of a yellowish-white opalescent colour, the large and somewhat curved caudal horn being black. The caterpillars were so transparent that under a low magnifying power the nervous, tracheal, and alimentary systems could be beautifully seen. As soon as the larvæ began to feed (on Epilobium parviflorum) they became green in consequence of the food appearing through the skin, but the latter also gradually acquired a dark green colour ([Pl. IV]., Fig. 17). All the specimens (some twenty in number) were exactly alike, and showed no trace of marking.
Second Stage.
The first ecdysis occurred after 5–6 days, the length of the caterpillars being from nine to ten millimeters. After this first moult they appeared of a shining green, the horn, which was black during the first stage, becoming a little red at the base, while a fine white subdorsal line extended from the horn to the head ([Fig. 18]). The head and legs were green; the divisions between the segments appeared as fine light rings, and the entire upper surface of the segments was also crossed by fine transverse rings, as was also the case in the first stage.