The American affinities of the Rott butterfly are in entire harmony with what is known of the other insects of the lignites of the Rhine, where, says Professor Heer:[AU]—“On retrouve également des types américains, qui appertiennent à l’Amérique tropicale et sous-tropicale.”
As to the flora of Radoboj, Professor Heer writes in the work just quoted (p. 96): “Les plantes de la zône tempérée sont représentées plus fortement qu’à Sotzka,” and of the latter place he says (p. 95), after speaking of types of the temperate zone: “Cependant ces espèces se trouvent fort à l’arrière-plan en comparison des formes tropicales et subtropicales, parmi lesquelles prédominent … les formes indo-australiens; néanmoins les formes américains, loin d’y faire défaut, sont représentées par des types assez nombreux et nettement accusés.” As a whole, therefore, the affinities of the tertiary butterflies seem to be precisely what we should have anticipated from a study of the vegetation of the period.
We close this portion of our subject with a tabular view of the results we have reached in considering the affinities of the tertiary butterflies with living types, in which the countries, where the living allies of the fossil forms are now found, are placed in the right-hand columns according to the degree of affinity of their inhabitants to the tertiary species against which they are placed.
| Aix—Upper Eocene. | Names of Butterflies. | Degree of Affinities. | |||
| FIRST DEGREE. | SECOND DEGREE. | THIRD DEGREE. | FOURTH DEGREE. | ||
| Neorinopis sepulta. | Indo-Malayan. | Austro-Malayan. | S. American. | ||
| Lethites Reynesii. | Indo-Malayan. | North temperate Zone. | |||
| Coliates Proserpina. | Indo-Malayan. | Austro-Malayan. | |||
| Thaites Ruminiana. | Mediterranean. | Chinese and Australian, Subarctic and Alpine. | |||
| Pamphilites abdita. | Tropical America. | Indo-Malayan. | |||
| Rott—lower miocene. | Thanatites vetula. | Subtropical North America. | North temperate Zone. | ||
| Radoboj—middle miocene. | Eugonia atava. | Subtropical temperate America. | North temperate Zone. | ||
| Pontia Freyeri. | Subtropical temperate America. | North temperate Zone. | |||
| Mylothrites Pluto. | African. | Indo-Malayan. Austro-Malayan. | |||
GENERAL RESUME, WITH NOTICES OF UNDETERMINED FORMS.
Nine well authenticated fossil butterflies are now known, all from the European Tertiaries; five of these have been found in the gypsum beds of Aix in Provence, southern France, belonging to the Ligurian, a division of the upper eocene; one in the lignites of Rott in the Rhenish Provinces of Prussia, belonging to the Aquitanian, or lower miocene; and three in the marls of Radoboj in Croatia, Austria, appertaining to the Mayencian or middle miocene. Our present knowledge, then, places the apparition of butterflies towards the end of the lower tertiaries.
As a general rule the specimens thus far discovered are in a fair state of preservation, and especially are those parts preserved which enable us, with considerable confidence, to determine their exact affinities. Three of these insects belong to the highest family of butterflies, Nymphales, four to the Papilionidæ, and two only to the Urbicolæ. If it be considered probable that the lowest of these families was the oldest, we can reasonably account for the scarcity of its members in the tertiary strata by the fact that their almost universally robust and muscular frame enables them to maintain flight when they have lost all but the merest stubs of wings. They would thus seldom meet their end by falling into pools of water, or if at last they did, it would be with fragments of wings whose affinities could not be traced. This supposition would be strengthened on noticing that one of the two fossil forms classed here, Thanatites vetula, belongs to a group of genera which comprises the very feeblest flyers in the family; and by the further consideration that two of the three fossil Nymphalids belong to the weak-winged Oreades. Eugonia, as well as Pamphilites, were doubtless strong and bold flyers; while the genera of Papilionidæ were moderately endowed. To proceed further in the analysis of their structural relations, two of the three Nymphales belong, as we have said, to the highest group of butterflies, the Oreades, represented now by the dark brown butterflies of our meadows; the remaining one to the Præfecti, a group of gaily attired butterflies with angulated wings like our common thistle butterfly, the cosmopolite. Of the four Papilionidæ, three belong to the Danai; two of these three to the group Fugacia, represented by our common yellow brimstone butterflies; the third to the Voracia, or white butterflies of the garden, so destructive to cabbages and other cruciferous plants. The fourth Papilionid belongs to the lower subfamily Papilionides; not, however, to that group which contains our swallow-tailed butterflies, but rather to an allied tribe, represented in America only by the Parnasii of the Rocky Mountain region. The two Urbicolæ are divided between the Hesperides and Astyci, the former closely related to the dingy, sylvan hesperians of early spring, seldom seen but by the naturalist; the latter to the tawny, brisk little skippers busy around the flowers in June.