Without going at present into the causes of these phenomena I will pass on to the consideration of further facts, and will now proceed to investigate both the form-relationships within the families. Here there can be no doubt that in an overwhelmingly large majority of cases the phyletic development has proceeded with very close parallelism in both stages; larval and imaginal families agree almost completely. Thus, under the group _Rhopalocera_ there is a series of families which equally well permit of their being founded on the structure of the larva or on that of the imago, and in which the larvæ and imagines therefore deviate from one another to the same extent. This is the case, for instance, with the families of the _Pieridæ_, _Papilionidæ_, _Danaidæ_, and _Lycænidæ_. But there are also families of which the limits would be very different if the larvæ were made the basis of the classification instead of the butterflies as heretofore. To this category belongs the sub-family _Nymphalinæ_. Here also a very characteristic form of caterpillar indeed prevails, but it does not occur in all the genera, being replaced in some by a quite different form of larva. In the latest catalogue of Diurnal Lepidoptera, that of Kirby (1871), 112 genera are comprised under this family. Of these most of the larvæ possess one or several rows of spines on most or on all the segments, a character which, as thus disposed, is not met with in any other family. This character is noticeable in genera 1 to 90, if, from those genera of which the larvæ are known, we may draw a conclusion with reference to their allies. I am acquainted with larvæ of genus 2, _Agraulis_, Boisd. (_Dione_, Hübn.); of genus 3, _Cethosia_, Fabr.; 10, _Atella_, Doubl.; 12, _Argynnis_, Fabr.; 13, _Melitæa_,[179] Fabr.; 19, _Araschnia_, Hübn.; 22, _Vanessa_, Fabr.; 23, _Pyrameis_, Hübn.; 24, _Junonia_, Hübn.; 31, _Ergolis_, Boisd.; 65, _Hypolimnas_, Hübn. (_Diadema_, Boisd.); 77, _Limenitis_, Fabr.; 81, _Neptis_, Fabr.; 82, _Athyma_, Westw.; and finally with those of genus 90, _Euthalia_, Hübn.--which, according to Horsfield’s figures, possess only two rows of spines, these being remarkably long and curved, and fringing both sides. It may be safely assumed that the intermediate genera would agree in possessing this important character of the Nymphalideous larvæ, viz., spines.