If the foregoing view be accepted, there follows from it a fundamental difference between the development of the genera _Chærocampa_ and _Deilephila_. In the former the formation of the eye-spots proceeds from a subdorsal line, but they first appear on two of the front segments, and are then transferred to the _posterior_ segments. In _Deilephila_, on the other hand, a single ring-spot is formed on the penultimate segment bearing the caudal horn, and this is repeated on the _anterior_ segments by secondary transference. With respect to the origination of the ring-spot also, there is a distinction between this genus and _Chærocampa_, inasmuch as the first step towards the eye-formation in the latter consists in the separation of a curved portion of the subdorsal line, whilst in _Deilephila_ the nuclear spot first seems to originate and the separation of the mirror-spot from the subdorsal line appears to occur secondarily. It is difficult here to draw further conclusions, since the first appearance of the primary ring-spot has not yet been observed, and no more certain inference respecting the history of the formation of the _primary_ ring-spots can be drawn from the manner in which the _secondary_ ring-spots are formed. Because in _Hippophaës_ the formation of the secondary ring-spots begins with the red coloration of one or two shagreen-dots, it does not follow that the primary spot on the eleventh segment also originated in this manner; and this is not without importance when we are concerned with the causes which underlie the formation of ring-spots. In _Chærocampa_ also, the formation of the primary eye-spots appears to differ from that of the secondary--in the latter the black “ground-area” first appearing, and in the former the “mirror-spot.” The secondary eye-spots certainly remain rudimentary in this last genus, so that the evidence in support of this conclusion is thus much weakened; but it must be admitted that we are here on ground still too uncertain to admit of wider conclusions being based thereon. As a final result of the investigation, we may advance the opinion that the existing species of the genus _Deilephila_ have reached five different phyletic stages, and that their very different external appearance is explained by their different phyletic ages; the appearance from these caterpillars of moths so extremely similar, can otherwise be scarcely understood. It may appear almost unnecessary to bring forward additional proofs in support of this interpretation of the facts, but in a field where the data are so scanty, no argument which can be drawn from them should be considered as superfluous. The variations which occasionally occur in the larvæ, however, to a certain extent furnish a proof of the correctness of the theoretical interpretation offered.