Chapter IV: Part 4

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The single fossil represented by von Heyden under the name of _Vanessa vetula_, is preserved on a greasy, dark brown, thin and exceedingly fragile sheet of “brown coal,” and is likely to become so affected by weathering as to be almost or quite indistinguishable in the course of time. Indeed it is excessively obscure at the present time, and no fossil object I have ever studied has proved so difficult to decipher as this. It represents an insect (Pl. III, fig. 12) lying upon its side in a somewhat natural attitude (compare fig. 11), so that one can see the whole of the under surface of the left hind wing, the costal quarter of the under surface of the left fore wing, and a little more than a quarter of the upper surface of the right fore wing, also of the costal area; the thorax and head with the eyes, the denuded palpi, the partially unrolled tongue and fragments of the legs in a confused medley may also be seen, but there is no trace of the antennæ, nor of the right hind wing (nor of the abdomen?). The left hind wing has an immaterial part of its outer border removed, and a small portion of the outer border of the left fore wing is also wanting, but the corresponding portion of the right fore wing is present. The markings can only be made out by extreme care, and a very meagre portion of the neuration, especially toward the borders of the wings, by great patience and the closest examination; but most of what can be seen of the neuration adds but very little to our actual knowledge of the animal; it simply adds its testimony in the same direction as other features of the object.

The illustration of von Heyden (Pl. III, fig. 16) is faulty in several particulars, but this is not surprising when we consider the excessively obscure nature of the fossil; it represents the insect as if the under surface of both wings of one side were seen, the fore wing concealing a portion of the hind; a break in the stone is taken for the outline of the wing (just above the extremity of the costal border of the hind wing) and the markings of the two front wings are blended into one; an abdomen is represented and above it an outline of the inner border of the hind wing. The fossil has at first sight this appearance, but I think this view is erroneous, although on this point one may not speak with confidence, and it is comparatively unimportant. It is remarkable, however, that von Heyden, in his _description_, takes the same view of it as I have done. I have not attempted to give the shading of the darker parts of the wing, partly from its obscure nature, partly from a doubt whether they really represent the original markings of the insect; for the basal half of the under surface of the hind wings, where most of the dark mottling in Von Heyden’s figure occurs, is usually devoid of any such variegation in the insects of this group; they are almost always of a uniform grayish or brownish hue. Von Heyden’s figure does not show the division of the palpal joints.

Tertiaries of Rott, Rhenish Provinces of Germany. British Museum.

URBICOLÆ—ASTYCI.

PAMPHILITES SCUDDER.

This genus belongs to the Astyci and falls in the neighborhood of Pansydia and Carystus, if we take as an illustration of the latter group the _Hesperia Lucasii_ of Fabricius. The former genus has a male with a discal dash, the latter without one. As the fossil species is represented by a single fore wing of what is probably a female, it is impossible to say into which category it would fall. The costal border (Pl. III, fig. 18) is almost exactly straight throughout; next the base, however, it is arched a little and it slopes slightly downward on the apical fifth to a rather sharply defined apex; the outer margin is gently and almost regularly convex, but with its greatest convexity a little above the middle, and at its upper end is at right angles to the tip of the costal margin; the lower angle is rounded off and the inner margin is slightly sinuous, being hollowed in the middle; the wing is slightly more than twice as long as broad. In all these respects it agrees far better with Pansydia (Pl. III, fig. 15) than with Carystus (Pl. III, fig. 13). Indeed, excepting in the greater length of the wing and the lack of any change of direction in the outer border at the tip of the lowest median nervule, the form of the wing scarcely differs from that of _Pansydia Mesogramma_.

In neuration it agrees better with Pansydia than with Carystus. Poey’s figure, which for want of better material I have been forced to copy in illustration, is not executed with sufficient care, for of the first and second superior subcostal nervules he has made but one. The principal difference between Pansydia and the fossil genus is in the fourth superior subcostal nervule; in Pansydia this terminates upon the costal border just before the apex of the wing, while in Pamphilites it terminates on the outer border just below the apex of the wing, bringing the latter into a different interspace in the two genera. From Carystus it differs, not only in having a proportionally shorter cell, but in the same point as that in which it is distinguishable from Pansydia; and further in the uppermost median nervule, which in Carystus is thrown off abruptly from the nervure just beyond its second divarication and which, by curving strongly, makes the upper median interspace of nearly equal width throughout; while in Pamphilites, the nervule parts gently from the nervure like the others, and at some distance beyond its second divarication, passing in a regular curved line to the outer border, and causing the upper median interspace to increase in breadth throughout the whole of its basal half.

In the disposition of its spots, Pamphilites (Pl. III, figs. 14, 17) agrees perhaps better with Carystus (Pl. III, fig. 19) than with Pansydia (Pl. III, fig. 15). This is especially true of the large spots in the cell and in the lower two median interspaces; although in Carystus the spots of the median interspaces are further removed from the base than in Pamphilites, while the opposite is true of the spot surmounting the submedian nervure; the submarginal spots beyond the cell of Pamphilites are wanting in Carystus, and the latter genus has but two of the three subcostal spots of Pamphilites. The spots of Pansydia are smaller and far less conspicuous than in Pamphilites, that of the cell being reduced almost to a dot; the median spots are however large, though removed farther from the base, as in Carystus; there is also a small spot in the upper median interspace, but further from the margin than in Pamphilites and unaccompanied by any spot in the interspace beyond the cell; as in Carystus, the spot surmounting the submedian nervure is further from the outer margin than in Pamphilites, but the subcostal spots accord very well with those of the fossil.

By these considerations it would appear that Pansydia is to be placed between Carystus and Pamphilites, the latter being more nearly related to Pansydia than to Carystus, leading us to believe it more probable that we are dealing with a female, whose partner was possessed of the ornament of a discal dash of specialized scales. The species of Pansydia are smaller than those of most of the neighboring genera, but _Pamphilites abdita_ is somewhat smaller even than _Pansydia mesogramma_.

PAMPHILITES ABDITA SCUDDER.

Pl. III, figs. 14, 17, 18.

Upon a dark, uniform, probably blackish brown ground, the fore wing of this butterfly was provided (in the female?) with three large spots, three small spots, and two dots of a vitreous appearance, besides other light streaks or powdery spots. The three large spots are probably peculiar, in their present extent, to the female; they consist (Pl. III, figs. 14, 17,) of one spot in the cell and one in each of the lower median interspaces; the cellular spot crosses the cell, is sublunato-quadrate, its exterior edge concave, extending from the origin of the third superior subcostal nervule to just beyond the second divarication of the median nervure, being directed in the upper half of its course toward the base of the second median nervule; the spot is narrower above than below, the upper half having an outward as well as upward inclination, the lower margin straight, the interior margin subsinuate, convex, reaching from midway between the base of the first and second superior subcostal nervules to just beyond the middle of the space between the base of the first and second median nervules. The spot in the lowest median interspace is nearly or quite as large as the previous, but longitudinal instead of transverse, and as broad as the interspace; excepting for a little spur above on the inner side, which runs a little way toward the base, the centre of the spot would lie just below the second divarication of the median nervure, but by means of this slight spur the spot extends baseward half way from the second to the first divarication of the median nervure; at the outer extremity the spot terminates squarely and next the lowest median nervule is two-sevenths the length of that vein. The spot in the middle median interspace is much smaller, subtriangular, filling the whole breadth of the interspace, half as long again as broad, its inner tapering extremity situated just below the final divarication of the median nervure. The three small spots in the lower three subcostal nervules are seated one above the other, their inner margins on a line and nearly at right angles to the costal margin; they are quadrate and increase slightly in size below, the upper one being square, the lower longitudinally oblong; they are situated midway between the discoidal spot and the apex of the wing. The two dots are situated one just above the other in the middle of the upper median and subcosto-median interspaces, midway between the spot in the lower subcostal interspace and the outer border; the lower is slightly the larger, but not more than one-fourth the size of the uppermost subcostal spot. Seated upon the submedian nervure, its centre below the outer edge of the lower median spot, is a pale, powdery spot, twice as long as broad and about one-third the width of the interspace; outwardly it merges into the ground color; there are other pale spaces in the wing, looking somewhat as if due to attrition; especially in the cell on either side of the discoidal spot, at the extreme base of the lower median interspace, and along the lower border of the medio-submedian interspace. Length of wing, 15·75mm., length of inner border, 9·5mm.; breadth of wing across the middle, 7·25mm., breadth of wing across outer margin, 9·5mm..

Tertiaries of Aix, Provence, France. Museum of the City of Marseilles.

COMPARATIVE AGE OF FOSSIL BUTTERFLIES.

All the well determined fossil butterflies come from one of three localities, Aix, Rott and Radoboj, all belonging to the tertiaries of Europe. Others are reported, as will be seen further on, to have been found in Prussian amber; and it is not in the least improbable that they have been or may be. These would be of about the same age as the oldest of the others, those of Aix. Of the Aix fossils, which belong to the upper Eocene, or to speak more definitely, the Ligurian, _Neorinopis sepulta_, _Lethites Reynesii_, _Thaites Ruminiana_ and _Pamphilites abdita_ (the first described by Boisduval, the rest by myself) come from the calcareous marls of the gypsum quarries, the only bed in which insects had been found when visited by Messrs. Murchison and Lyell in 1829. _Coliates Proserpina_, however, described here for the first time, was taken from strata beneath these, and therefore, at least until we have more precise knowledge concerning the remains of butterfly larvæ in amber, may be considered the oldest known butterfly. Count de Saporta writes me concerning this fossil, the discovery of which is due to him, as follows:—“Cette empreinte ne provient pas des platrières même, c’est à dire des galeries qui servent à l’exploitation du Gypse; mais d’une assise ou groupe de couches immédiatement inférieure. Vous verrez cette provenance indiquée pour un grand nombre de mes espèces; dans ce cas, elles ne proviennent par des ouvriers mais je les ai recueillies moi même en suivant les lits sur les points où ils affleurent au dehors.”

The next in order, approaching recent times, are the lignite beds of Rott in the basin of the Rhine, which belong to the Aquitanian or the upper part of the lower Miocene. _Thanatites vetula_ (described by Hayden) is the only butterfly known from this division of the Tertiaries.

The most recent beds containing fossil butterflies are the lacustrine deposits of Radoboj in Croatia, Austria. These belong to the Mayencian or lower portion of the middle Miocene, and have furnished _Eugonia atava_, _Mylothrites Pluto_, another fragment possibly referable to Mylothrites, and _Pontia Freyeri_, all described by Heer. Two of the genera of these more recent beds contain representatives now living in the same region; but none of the older beds have yet furnished butterflies referable to modern genera.

It is rather extraordinary that the upper Miocene beds of Œningen, Bavaria, which, if we except the amber, have furnished almost more insects than all the other beds of fossil insects of the world together, and which are more recent than any of those in which butterflies have been found, have yielded scarcely any remains of Lepidoptera (one species) and none whatever of butterflies.

PROBABLE FOOD-PLANTS OF TERTIARY CATERPILLARS.

Of the five butterflies from Aix, two belong to the Oreades (_Neorinopis sepulta_ and _Lethites Reynesii_) the food of whose caterpillars at the present epoch has invariably been found to be either Gramineæ or, occasionally, Cyperaceæ. Both of these groups are present in the deposits of Aix, the former being represented by ten species of Poacites, and the latter by a Cyperites;[AG] and it is in the highest degree probable that these formed the sustenance of the Oreades of that epoch. A third species (_Pamphilites abdita_) belongs to the Astyci, a group whose principal food is the same family of plants, Gramineæ, although some species have been found also upon Althea, Malva and Lavatera (Malvaceæ), Trifolium, Coronilla and ?Lespedeza (Leguminosæ), Plantago (Plantaginaceæ), and Maranta (Scitamineæ). Of these families the Leguminosæ only are found at Aix, and in abundance, even including a plant doubtfully referred to Trifolium. It is, however, far more probable that Pamphilites lived upon grasses; and it is not a little strange that the Gramineæ, the probable food-plants of three of the five butterflies known from that fauna, were among the rarest of the plants; that is, their proportion to the whole phanerogamic flora was about the same as now obtains in New Guinea or New Grenada, countries the least favored in this respect.[AH] The proportion of the Gramineæ and Cyperaceæ to the whole of the Phanerogamia in Europe of to-day is, probably, about the same as in the United States (more than seventeen per cent.) and much greater than in the East Indies. The limited number of known fossil butterflies does not give great weight to any general considerations based upon them, but it may at least be worth while to remark that Aix, in Eocene times, had, in the point referred to, an assemblage of plants much better comparable with the East Indian flora of the present day than with the modern European flora, the proportion of known Gramineæ, etc., to the Phanerogamia being five per cent., while the proportion of its grass-feeding butterflies to the other rhopalocerous Lepidoptera is sixty per cent. To judge simply by the catalogue of the East India Museum, the only authority upon East Indian butterflies extant, the present proportion of gramnivorous to non-gramnivorous butterflies is as 1: 5·2, while in Europe it is as 1: 3. Eocene Aix, then, had a European proportion of Satyrids, composed, as will be seen, of species of an Indian aspect, feeding upon plants essentially temperate, but, as in tropical countries, numerically unimportant.

The Danai, to which the fourth species from Aix (_Coliates Proserpina_) belongs, feed almost exclusively upon Leguminosæ, and these have recently been found in great abundance at Aix. Count de Saporta enumerates one species each of ?Trifolium, Caragana, Ervites, Sophora, Micropodium, Cercis and Gleditschia, two of Phaseolites and six of Cæsalpinites, belonging to the Papilionaceæ, besides nine Acacias and a Mimosa of the Mimoseæ, and four species of uncertain relations; making a series larger than he has found in any other family.[AI]

Of these, two species of Phaseolites, one of Sophora, eight of Acacia and two of Leguminosites are specified as coming from the lower beds, where Coliates itself is found. But Coliates is most closely allied, as we have said, to a group of Indian forms, and the food plants of their caterpillars is almost wholly unknown. A species of Delias, however, to which genus Coliates has been specially compared, is stated to feed, not upon a leguminous plant, but upon Dioscorea, one of the Yam family; and the presence in Aix of a species of a closely allied group, _Smilax rotundiloba_ Sap., is announced by Count de Saporta. It is not improbable, therefore, that _Smilax rotundiloba_ was the food-plant of the larva of _Coliates Proserpina_.[AJ]

The fifth Aix species is _Thaites Ruminiana_. It is most nearly allied to Thais of the present day, though it bears certain relations, as we have seen, to neighboring genera. Thais feeds principally at least upon Aristolochia[AK] and so, too, do Ornithoptera, Archon and some genera of swallow-tails; indeed, this seems to be a favorite food-plant with insects of this character. Parnassius, however, feeds on Sedum, Telephium, Sempervivum and Corydalis, especially on the first-named, one of the Crassulaceæ; but nothing very closely allied to this is specified by Saporta from Aix; neither, also is Aristolochia, but it has been found not only in Radoboj[AL] in the Mayencian, but also, according to Heer, at Hohe Rhonen in Switzerland, which belongs to the Aquitanian, and has at least one plant (_Laurus primigenia_ Ung.) in common with Aix. It seems, therefore, highly probable that either _Aristolochia nervosa_ Heer, _A. Aesculapi_ Heer, or a distinct species of the genus will yet be discovered at Aix,[AM] and may then be considered, as with little question, the food-plant of _Thaites Ruminiana_. If it be deemed hazardous to venture such an opinion, attention is called to the two following passages; the first is from the introduction to Heer’s paper on the fossil insects of Aix:[AN] “Dass indessen auch Weiden oder Pappeln [Populus] sich vorhanden, dürften der Bythoscopus muscarius und die Aphrophora spumifera [Homoptera] anzeigen, deren analoge lebende Arten besonders auf den Blättern und Zweigen dieser Bäume sich umhertreiben.” The second is a note in the errata to the translation of Heer’s work on the Climate and Vegetation of the Tertiaries[AO] by Gaudin: “Le Poacites ciliatus Sap. n’est pas une glume de Graminée, mais plutôt une bractée ciliée de Peuplier.… Elle doit être probablement rapprochée d’une empreinte … provenant des mêmes couches et qui se rapporte également au genre Populus. Les organes voisins de ceux du Pop. Euphratica Oliv. dans la nature actuelle dénotent l’existence, à l’époque des gypses d’Aix, d’une espèce de Peuplier dont les feuilles sont encore inconnues, comme celles de l’Alnus cryptophylla Sap., mais que M. Heer avait indiqué d’avance, en se fondant sur l’observation d’un insecte fossile, le Bythoscopus muscarius! Nouvelle preuve du secours que peuvent se prêter en paléontologie les diverses branches de l’histoire naturelle.”

The single species from Rott, _Thanatites vetula_, is closely allied to the modern Thanaos, whose species are numerous and feed upon a variety of plants, belonging to the families Cruciferæ, Leguminosæ, Umbelliferæ, Cupuliferæ, Betulaceæ and Salicaceæ. Most of the genera belonging to its tribe feed upon Leguminosæ, and these are the usual food plants of the species Thanaos also; whence it is probable that Thanatites had a similar taste. Now in the very beds of Rott, in which this butterfly was found, occur species of Betula, Salix and Populus, with numerous Querci and no less than eleven genera of Leguminosæ, mostly belonging to the Papilionaceæ; they are Templetonia (1 species), Robinia (2), Colutea (1), Phaseolites (2), Sphinctolobium (1), Dalbergia (1), Hæmatoxylon (2), Gleditschia (2), Cassia (3), Ceratonia (1), and Acacia (2). It is probably among these, and perhaps with greatest probability among the species of Hæmatoxylon and Gleditschia, that the food plant of Thanatites must be sought. Should leaves be found, in which a portion is bent over as if to form a nest, they should be submitted to the scrutiny of some one familiar with the larval habitations of _Thanaos Tages_; and should traces of silken fastenings be found in connection with them, or the marks of nibbling at the edges, the plant to which they belong may be considered with strong probability as the food of _Thanatites vetula_.

The only butterfly found at Radoboj belonging to an extinct genus is _Mylothrites Pluto_, and this is a member of the same general group as Coliates, and feeds probably upon Leguminosæ; for it is not so closely allied to Delias as Coliates is, but is more nearly related to Hebomoia, one of whose species, found in the East Indias, feeds upon Capparis.[AP] One species of Phaseolites, one of Sophora and four of Cassia, namely: _C. hyberborea_ Ung., _C. phaseolites_ Ung., _C. lignitum_ Ung., and _C. ambigua_ Ung., are recorded from Radoboj, and as Cassia is a favorite food plant among the larger species of Danai at the present day, we may fairly presume one of these Cassiæ to have afforded nourishment to _Mylothrites Pluto_. Moreover, no less than thirty-one species of Leguminosæ in general, or between a ninth and a tenth of the whole known flora, are given by von Ettingshausen as occurring in Radoboj; so that in any case our Mylothrites must have found abundance of palatable food.

The food of _Pontia Freyeri_ is doubtful. All the living species of the genus so far as known, feed upon Cruciferæ; within this family they do not seem to be at all particular, making use of a large number of genera, but in only a single instance are they known to attack the leaves of a genus (Reseda) belonging to an adjoining family. Cruciferæ, however, are excessively rare in the tertiaries of Europe, two species only being recorded, and this from the comparatively recent beds of Œningen. This is unquestionably due simply to the nature of the plants themselves, which scarcely could leave any trace of their existence; the almost complete absence of the herbaceous families of plants, even in the later tertiaries, is doubtless due to this fact. The plants nearest related to the Cruciferæ found near the horizon of _Pontia Freyeri_ are a species of Nelumbium from Günzbourg in the Mayencian, and of Terminalia (_T. radobojensis_ Ung.)—one of the Calycifloræ, from Radoboj itself. Perhaps in the absence of better evidence we may provisionally consider the latter to have been the food plant of _P. Freyeri_.

A single Radoboj species remains, _Eugonia atava_. The recent species of Eugonia feed particularly on Salix, Populus and Betula; also upon Ulmus, and occasionally on Ribes, and even on Hippophae. The first three seem however to be their proper food; and since the tertiaries of Radoboj contain fossils of all these genera, we need look no farther. There are specified: _Salix apollinis_ Ung., sp., _Populus latior_ Br., _P. mutabilis_ Heer., _P. Heliadum_ Ung., _Betula Dryadum_ Brongn. and _B. prisca_ Ett. Three species of Ulmus are also recorded from the same place.

Excepting in a single case, there is then no difficulty in finding, in the very hods in which the butterflies occur, remains of plants, which in all probability served them as food during the larval stage; and even in this single instance, a plant not far removed from those upon which species of the genus now feed, occurs in the same strata.

PRESENT DISTRIBUTION OF BUTTERFLIES MOST NEARLY ALLIED TO FOSSIL SPECIES.

To discuss this question properly we must consider the butterflies of each geological horizon separately.

BUTTERFLIES OF THE LIGURIAN (Upper Eocene).

The nearest living ally of _Neorinopis sepulta_ is, with little doubt, _Neorina Lowi_, which, like the other members of the genus, is found in the Indo-Malayan region. The same is strictly true of the species of Zophoessa, Debis and Lethe, with which we have been obliged to compare this fossil. Cœlites has also been used in comparison, and most of the species of this group belong to the same region, although one is described by Felder from Celebes on the confines of the Austro-Malayan region. We have also pointed out (as Butler has done, but in incorrect points) its relation to Antirrhæa, a Brazilian genus, but this is too distant to be given much weight. The closest allies of _N. sepulta_ are to be found in the Indo-Malayan region.

The same is true, but not to so striking a degree, of _Lethites Reynesii_. We have compared this also to Debis, Lethe and Neorina, and especially to the two former; and all three of these genera, which are certainly its nearest allies, are strictly confined to the Indo-Malayan region. It is, however, also related, but in a secondary degree, to Enodia, Cercyonis and Maniola, which are genera appertaining to the north temperate zone of both hemispheres.

_Coliates Proserpina_ finds its nearest living representatives in the genus Delias, which also is strictly confined to the Indo-Malayan region. Thyca and Prioneris are closely related, the latter of which is limited to the same district and the former to the Indo-Malayan and Austro-Malayan regions.

_Thaites Ruminiana_ is represented in recent times by the genus Thais, which is confined to the Mediterranean district, within which Aix lies. An allied genus, Archon, is also restricted to the same region. Sericinus, however, and Eurycus, with which we have been obliged to compare it in many points, are found only in the East, the former in China, the latter in Australia; while on the other hand, Parnassius, a genus it quite as much resembles, is limited to alpine and subarctic regions of the northern hemisphere.

The relations of _Pamphilites abdita_ are very different. I have searched carefully for very closely allied forms among East Indian Urbicolæ; but, while it doubtless is not far removed from some of them, its more intimate relationships are certainly with insects from tropical America and especially with Pansydia and Carystus.

Three out of the five Aix butterflies, therefore, find their nearest living allies in the Indo-Malayan region, one is most closely related to forms now found in tropical America and one is at home in its own resting place.

BUTTERFLIES OF THE AQUITANIAN (Lower Miocene).

_Thanatites vetula_ is the only butterfly yet found from this horizon, and this is closely related to Thanaos, a genus belonging to the north temperate zones of both hemispheres, but vastly more developed in the new world, which has at least four times as many species as the old, some of them extending into the subtropical regions. The genera adjacent to Thanaos are purely American, although tropical or subtropical, and therefore the Aquitanian butterfly looks toward subtropical North America for its relatives of the present day.

BUTTERFLIES OF THE MAYENCIAN (Middle Miocene).

Only a single one of these butterflies, _Mylothrites Pluto_, belongs to an extinct genus. Its nearest living representatives are to be looked for in the genera Mylothris and Hebomoia, the former of which finds its highest development in torrid Africa, while the latter is confined to the Indo-Malayan and Austro-Malayan regions.

The other two belong to modern genera, Eugonia (_E. atava_) and Pontia (_P. Freyeri_). These two genera are very similar in their distribution, spreading, like Thanaos, above referred to, over the north temperate regions of both hemispheres. Eugonia, however, is represented equally in Europe and America, while Pontia is considerably richer in species in the Old World than in the New; yet when we look into the distribution of the neighboring genera we shall find a result somewhat similar to the case of Thanaos. Taking into consideration, in the one case, the present distribution of the genera Hypanartia, Polygonia, Papilio and Hamadryas,[AQ] and on the other of Neophasia, Tatocheila and Leptophobia, we shall find that the largest development of these groups of genera has been in the New World rather than in the Old, but in those parts of the New World which lie on the tropical confines of the temperate zone.

Two of the more recent species of fossil butterflies are therefore at home where they are found, although the present development of the group of genera to which they belong finds its fullest expression in America; while the third species follows most of those from the lower tertiaries in seeking its allies of to-day in the tropics of the old world.

* * * * *

Undoubtedly the material at our disposal is, as we have already remarked, far too meagre to present any generalities of importance, so long as they are unsupported by external proof. This aid we can claim in considering the facts we have presented concerning the present distribution of the genera of butterflies most nearly allied to those once living in the neighborhood of Aix. The careful researches of Count Saporta upon the rich flora of this region at the same epoch, points to very nearly the same results as are here indicated. In his _Examen des flores tertiaires de Provence_,[AR] when writing of the characteristics of the Aix flora, Count Saporta says (page 150) that about one-fifth of the families represented in it are now strangers to Europe; that fifty-one genera have an exotic and more or less tropical aspect, and that forty out of seventy-four, or about one-half, if not exclusively tropical, inhabit the warmer parts of southern regions, or, in small numbers, temperate extra-European countries. The result is still more striking, if species are considered, of which there are at least eighty whose individual analogy with living species is sufficiently clear to yield results of great probability. “De ces espèces,” to use his own words, “12 seulement correspondent à des espèces de l’Europe moyenne, 6 à des espèces de l’Europe méridionale, 18 en tout. Les espèces correspondant à des formes de l’Amérique septentrionale ou des régions élevées de l’Amérique tropicale, sont au nombre de 10; celles qui répondent à des formes de l’Amérique tropicale s’élèvent à 9 …; 3 correspondent à des espèces du Cap et 2 à des espèces des îles Atlantiques et de la Barbarie; 14 représentent des formes particulières aux Indes ou aux îles de l’Archipel indien et 30, enfin, correspondent à des formes australiennes. Le groupe australien est donc le plus considérable, si on les prend isolement. En les réunnissant, on voit que sur les 80 et quelques espèces, 28 à 30 seulement correspondent à des formes habitant aujourd’hui l’Europe et l’Amérique du Nord, en y comprenant même les parties méridionales de ces continents; tandis que 57 au moins, soit 60 en nombre rond, représentent des formes tropicales ou subtropicales, et dans ce nombre 40 au moins, c’est-a-dire la moitié du nombre total se rapportent au Cap, aux [151] Indes orientales où à l’Australie; de sorte que le caractère dominant de cette flore est encore Austro-indien, quoique dans une proportion déjà décroissante par rapport à l’âge précédant.”

This was published in 1861, and would accord entirely with what we know of the butterflies of Aix and their nearest allies. But eleven years later, after studying the great amount of material which had meanwhile accumulated, Saporta seems to have reached different conclusions, for in his _Revision de la Flore des Gypses d’Aix_ he states that the affinities of the eocene vegetation of Aix are with southeastern Asia and with Africa, and lists of analogous species are given, showing that twenty-two Aix species are to be compared with similar types in Asia, and forty with those of Africa. So that African forms much surpass the Asiatic in the eocene flora of Aix. This is particularly true, he says, with reference to the region of Africa between Abyssinia and the Cape of Good Hope. “C’est là évidemment le pays qui nous offre le tableau le plus ressemblant de ce que devait être le midi de la France, et c’est aussi vers ce même pays, ne l’oublions pas, que nous avons été ramenés par l’examen des autres élémens de la flore, spécialement par la proportion relative des deux grandes classes et des familles prédominantes.”[AS] The African element seems to be almost altogether wanting in the eocene butterflies, while the Asiatic predominates. In a chart accompanying Count Saporta’s paper, however, he represents the present limits of the _principal genera_ noticed in the flora of the gypsum of Aix by means of colored lines. These lines cluster remarkably along the southern borders of Asia and extend over a large part of Africa and across the ocean to America, and particularly toward the southern United States and the Antilles. Based on the distribution of these principal genera alone, the flora of the southern border of Asia would show a closer affinity to that of eocene Aix than would that of any equivalent belt in Africa; and if we may suppose that our relics of butterflies represent the principal genera then existing, we should trace a somewhat similar chart, but for the entire absence of African types; for subtropical American types mingle with those of the Mediterranean district and especially with those of the Indo-Malayan region. Count Saporta shows in his memoir just quoted, as before, that the relations of the eocene flora of Aix to that of the present Mediterranean basin were more restricted than its relations to exotic types, but in a letter to me he writes: “Ces affinités [les affinités présumées de la flore d’Aix] sont d’une part avec la région Méditerranéen, de l’autre avec l’Afrique et les Indes orientales. Les affinités miocènes avec l’Amérique sont postérieures.” These later American affinities are, however, foreshadowed among the plants and also, as we have seen, in the Pamphilites of eocene Aix. They appear again, and very decidedly, when we reach the miocene itself, for the affinities of the butterfly from Rott, and two of the later butterflies from Radoboj (where first we meet with truly modern types), are certainly with America in the first instance, and secondarily with the whole north temperate zone. While the last of the Radoboj butterflies shows still the remains of the earlier affinities of the Aix flora in finding its nearer existing types in Africa and southeastern Asia. The results we reach in considering the Aix butterflies are not, however, in accordance with those drawn from the insects of the same locality by Professor Heer. He writes:[AT]—

“A Radoboj, … on rencontre une plus forte proportion de formes
tropicales [than at Œningen].…

Cette faune des insectes s’harmonise parfaitement avec le flore
de Radoboj qui, ainsi que nous l’avons prouvé précédemment,
a un caractère plus méridional que celle d’Œningen; ce qui
s’expliquerait par sa plus grande ancienneté.

Comme il résulte des recherches de M. G. de Saporta qu’Aix
appartient à l’étage ligurien, on devrait s’attendre à y
rencontrer encore plus de formes tropicales qu’à Radoboj. C’est
tout le contraire, si bien qu’en m’appuyant sur la faune et
en voyant que Aix avait 10 espèces en commun avec Radoboj et
4 avec Œningen, j’avais rapporté précédemment les terrains
d’Aix à la même époque que ceux de Radobo; et je les avais
rangés dans le Mayencien. Quatre genres ont disparu.… Tous
les autres genres vivent encore dans la Provence, mais ce
sont, comme à Œningen, presque tous des genres qui occupent
une aire géographique très vaste.… On ne peut pas dire que la
faune des insectes d’Aix contredise positivement l’idée que
cette localité avait un climat sous-tropical, cas presque tous
les genres que l’on y a observés jusqu’à présent s’étendent
jusque dans la zône sous-tropicale, néanmoins cette faune ne
fournit que bien peu de preuves positives, tandis que, comme
M. de Saporta l’a démontré, la flore est riche en formes
méridionales.”

It should be remarked, however, that the insect fauna of Aix is as yet little known; that these observations of the learned Zurich Professor were founded upon a material exceedingly meagre, in comparison with the present vast accumulations of the museums of Marseilles, Paris and Aix; we may hope soon to become familiar with them through the careful researches of M. Oustalet; and these will show that the beds of Aix are, perhaps, even richer in fossil insects than those of Œningen.

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.

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.

But a single family of butterflies, then, is unknown in a fossil state,—that of Rurales; and since this comprises, in the main, insects of exceedingly delicate structure and of small size, their absence is by no means unaccountable. Yet, as we shall see further on, there are intimations of the presence of some of their caterpillars in amber, and an obscure and doubtful reference to a fossil Polyommatus from the beds of Aix.

If we enquire where the allies of these nine fossil butterflies are now living, we must seek for those of four of them in the East Indies; for those of three of them in America, and especially in that part lying on the confines of the tropical and north temperate zones; for those of one of them in the north temperate zone of both Europe-Asia and America; and for those of one in the Mediterranean district; for those of two only, therefore, out of the nine, or less than one-fourth, in the region where the fossils were discovered. Analyzing this point still further, we notice that three out of the four species whose living allies are to be sought in the East Indies come from the older deposits of Aix, and that only one of the two remaining Aix species shows special affinities to American types; we thus find here, as among other insects and among the plants, a growing likeness to American types as we pass upward through the European tertiaries.

The study of the floras of the European tertiaries has proceeded so far that in most cases we are able to find, in the very beds where the butterflies occur, plants which we may reasonably judge to have formed the food of these insects in their earlier stages. In but a single instance is the family of plants, upon which it was necessary, or almost necessary, to suppose the caterpillar fed, entirely absent from tertiary strata; and since this family is the Cruciferæ, which in its very nature could scarcely have left a recognizable trace of its presence, the exception has no force.

After presenting these facts, for convenience sake, in a tabular form, we will pass on to the enumeration of those fossils which have been referred to butterflies, but whose exact position is still unsettled.

TABULAR VIEW OF FOSSIL BUTTERFLIES.

In the earliest accounts that we have found, including all those in the last century, the generic term Papilio was used for all Lepidoptera, and therefore we cannot be certain whether butterflies or moths are meant. Hueber’s plates, even, are so inferior that they afford no additional aid; but those of Sendel possibly represent, as we have noticed in the Bibliography at the commencement of this memoir, the early stages of butterflies preserved in amber. The only other direct references to butterflies preserved in amber are the following: Gravenhorst,[AV] in his enumeration of amber insects, gives under the Lepidoptera forty specimens referable to Tineæ and Tortrices, and besides these “mehre Raupen, sämmtlich, wie es scheint, Schildraupen, denen des Papilio W. album ähnlich.” The probable nature of the ancient forest yielding amber renders it unlikely that any butterflies in their perfect state would be found in it. As a rule, butterflies are eminently fond of the light. This has already been remarked by Menge:[AW]—“Das fehlen gröszerer Schmetterlinge im bernstein deutet auf einen finstern undurchdringlichen urwald, den die kinder des lichts gemieden haben.” Yet as some Theclas do feed upon coniferous trees, it is not impossible that the onisciform larvæ, referred to by Gravenhorst, may belong to this group. As far as we can discover, no further reference is made to them, excepting by Giebel and Bronn in some of their lists and enumerations of fossil insects. The writings of Berendt, Menge and others, all bear testimony to the great rarity of Lepidoptera in amber, and most of those which have been discovered belong to the lowest two families, above referred to.

Dr. Hagen informs me that he has himself seen specimens of large butterflies in amber, but that these proved to be falsifications, recent European insects like _Pieris rapæ_, etc., having been enclosed between slabs of amber, which were then fastened together and the edges roughened, all in so clever a manner that one would not suspect them to be spurious. These specimens were manufactured many years ago, and it is not impossible that it is to one of them that Hope refers in 1836, as found in the collection of Mr. Strong, though why he should quote Berendt as authority I cannot discover.

Heer, in the introduction to the lepidopterous portion of his “Insektenfauna der Tertiärgebilde von Œningen,” says (p. 175): “Karg erwähnt zwar eines sehr schönen Œninger-Schmetterlings, der nach Zürich gekommen sein soll. Allein hier findet sich dieser nicht und die Angabe verliert noch mehr an Werth, wenn wir berücksichtigen, dass Karg das Thier nicht selbst gesehen hat.” Karg’s memoir in the “Denkschriften der Schwäbischen Gesellschaft der Aerzte und Naturforscher,” T. I., I have been unable to examine.

Boisduval, in his final report upon _Neorinopis sepulta_, remarks that Count Saporta had written him that many years previously he had sent to the Paris Museum a “Polyommate fossile” from Aix. Count G. de Saporta, in reply to my inquiries concerning this specimen, says that his father can give me no further information concerning this specimen; nor could M. Oustalet and myself, in our search through the fossil insects of the Jardin des Plantes, discover any such relic.

In a recent number of “Nature” (No. 266), Mr. E. J. A’Court Smith writes of the discovery at Gurnet Bay in the Isle of Wight, of an insect bed in which were found, among other things, “a variety of flies, butterflies, and one or two grasshoppers;” no further information has yet been published concerning these relics, and my inquiries upon the subject have not, as yet, elicited any definite response.

NOTICE OF INSECTS WHICH HAVE BEEN ERRONEOUSLY REFERRED IN RECENT TIMES TO BUTTERFLIES.

1. _Cyllonium Boisduvalianum_ WESTW., and _C. Hewitsonianum_ WESTW.

Cyllonium Boisduvalianum Westw.]

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Fossil ButterfliesChapter IV: Part 4

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