In most species these ring-spots occur on many segments (10-12) (Fig. 117, _B_), and in cases where they are of importance in making the caterpillar conspicuous and easily seen they sometimes form a double row. But we know one species, _Deilephila hippophaës_, in which only a single ring-spot exists, and it is a large brick-red spot on the second last segment, mimicking the red berry of the buckthorn (Fig. 8, _A_ and _B_, _r_). But individuals also occur in which there are, on the five or six segments in front, smaller ring-spots which become less distinct the further forward they are, and in most caterpillars it is possible, on careful examination, to recognize little red dots on the faded sub-dorsal stripes of these segments (Fig. 8, _B_). We might be disposed to think, on this account, that the ancestors of _D. hippophaës_ bore rings on all the segments, and that these had gradually become vestigial on the majority of them, because they had lost their earlier biological importance, and now, by adaptation to the buckthorn, could only be of use on the second last. But when we take the ontogeny also into account we find in the young caterpillar only a simple sub-dorsal line, upon which, in the third stage, the red spot of the tail-horn segment appears (Fig. 8, _A_). No spots ever occur on the other segments at this stage; they only appear in the last stage, but as they may be entirely wanting, they must have arisen as the result of internal laws of correlation, that is, they must be recapitulations of the hindmost spots which arose in the phylogeny through natural selection. We may conclude this, at least, if we believe in the truth of the fundamental proposition of the biogenetic law, and admit that there is in the ontogeny some more or less distinct recapitulation of the phylogeny. [Illustration: FIG. 118. Two stages in the life-history of the Spurge Hawk-moth (_Deilephila euphorbiæ_). _A_, first stage, the caterpillar dark blackish-green, without marking. _B_, second stage, the row of spots is distinctly connected by a light streak, the vestige of the sub-dorsal stripe.]