The marking is only completely changed in the fifth and last stage. A broad reddish-brown dorsal line replaces the subdorsal, more or less completely. The supra-spiracular line also becomes broken up into numerous short lengths, whilst the green ground-colour in some specimens becomes more or less replaced by a brownish shade extending from the back to the sides. Horn, black; the upper part of the first segment with a corneous plate, similar to that of the _Deilephila_ larvæ. This stage is very variable, as shown by the figures in various works. The variations arise on the one hand from the struggle between the green ground-colour and the reddish-brown extending from above, and, on the other hand, from a more or less complete disappearance of the associated longitudinal lines. The latter are sometimes completely retained, this being the case in a caterpillar figured by Hübner (_Sphinges_, III., _Legitimæ_ C, b), where both the subdorsal and supra-spiracular lines are continuous from segment 11 to segment 1, an instance which may perhaps be regarded as a reversion to the primary form. The entire change of the marking from the fourth to the fifth stage depends upon the fact that the young larvæ resemble the _needles_ of the pine, whilst the adults are adapted to the _branches_. I shall return to this later. The ontogeny of _A. Pinastri_ makes us acquainted with three different forms of marking: (1) simple coloration without marking; (2) a marking composed of three pairs of parallel longitudinal lines; (3) a complicated marking, arising from the breaking up of the last and the addition of a darker dorsal line. Of the fourteen species placed by Gray in the genus _Anceryx_, I find, in addition to the one described, notices of only two caterpillars:-- _A. Coniferarum_,[123] a North American species, lives on _Pinus Palustris_, and was figured by Abbot and Smith. Colour and marking very similar to _A. Pinastri_. _A. Ello_, Linn.,[124] according to the authority of Mérian, is described by Clemens[125] as dark brown, “with a white dorsal line, and irregular white spots on the sides.” It lives on a “species of _Psidium_ or _Guava_.” Most of the species of _Anceryx_ appear to live on _Coniferæ_, to which they show a general and decided adaptation. In the absence of decisive information, I partly infer this from the names, as _Anceryx Juniperi_ (Africa). It has long been known that in our _A. Pinastri_ the mixture of brown and fir-green, interspersed with conspicuous irregular light yellowish and white spots, causes the adult larva to present a very perfect adaptation to its environment. Of this caterpillar Rösel states:--“After eating it remains motionless, and is then difficult to see, because it is of the same colour as its food, since its brown dorsal line has almost the colour of the pine twigs; and who is not familiar with the fact that beneath the green needles there is also much yellow to be found?”