This character of the number of spines will not be considered as too unimportant when we observe how perfectly constant it remains in the nearly allied species. This is the case in the three consecutive forms, _Urticæ_, _Polychloros_, and _Ichnusa_. Now when we see that two species which differ in their imaginal characters present correspondingly small differences in their larvæ, this exact systematic congruence indicates a completely parallel phyletic development. Exceptions are, however, to be met with here. Thus, Hübner has united one group of the species of _Vanessa_ into the genus _Pyrameis_ just mentioned, on account of certain characteristic distinctions of the butterflies. I do not know, however, how this genus admits of being grounded on the structure of the larvæ; the latter, as appears from the above table, agree exactly in the number and position of the spines with the caterpillars of _Vanessa_ (_sensû strictiori_), nor can any common form of marking be detected which would enable them to be separated from _Vanessa_. Still more striking is the incongruence in the genus _Araschnia_, Hübn. (_A. Prorsa-Levana_), which, like the genus _Pyrameis_, is entirely based on imaginal characters. This is distinguished from all the other sub-genera of the old genus _Vanessa_ by a small difference in the venation of the wings (the discoidal cell of the hind-wings is open instead of closed). Now it is well-known that in butterflies the wing-venation, as most correctly shown by Herrich-Schäffer, is the safest criterion of “relationship.” It thus happens that this genus, typified by the common _Levana_, is in Kirby’s Catalogue separated from _Vanessa_ by two genera, and according to Herrich-Schäffer[188] by forty genera! Nevertheless, the larvæ agree so exactly in their spinal formula with _Grapta_ that we should have no hesitation in regarding them as a species of this sub-genus. It appears to me very probable that in this case the form-relationship of the caterpillar gives more correct information as to the blood-relationship of the species than that of the imago--in any case the larvæ show a different form-relationship to the imagines. Just as in the case of butterflies there are many genera of _Sphingidæ_ which can be based on the structure of the larvæ, and which agree with those founded on the imagines.