Part 8

Dark brown or blackish with light markings. On the upper half of the fore wing (Pl. III, fig. 12), both above and below, the following markings are found: a small quadrate spot on the costal border at the extremity of the costal fold; depending from the costal border between the tips of the second and third superior subcostal nervures a confluent series of spots extending to the cell at right angles to the costal margin, narrowing a little in passing downward; and midway between this and the outer border, in the upper two subcostal interspaces opening on the outer border, a small round spot; probably similar spots belong in some of the interspaces below. On the under surface of the hind wings there is a submarginal series of three small spots along the costa at equal distances apart, the central one near the middle of the costa, and the basal one nearly midway between it and the base of the wing; there is also a larger spot near the tip of the cell and a second smaller one a little below and beyond it; also a submarginal series of spots as large as that in the cell parallel to the outer border, at about an interspace’s distance from it, one in each interspace. Length of fore wing, 14mm.; length of hind wing, 13·65mm.; extreme breadth of hind wing, 11·25mm..

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.