ART. XXXII.-THE FOSSIL INSECTS OF THE GREEN RIVER SHALES. BY SAMUEL H. SCUDDER, CAMBRIDGE, MASS. The following descriptions are published to afford some notion of the nature and extent of the insect remains found in the immediate vicinity of Green River Station on the Union Pacific Railroad in Wyoming. Illustrations of all of them have been prepared for a general work on the Tertiary insects of North America, to be published by this Survey. With a very few exceptions, the specimens were found in a restricted basin, about six kilometres west of the town, exposed by a railway cutting called the "Petrified Fish Cut", from the vast number of fish remains discovered here in building the road. The insects were obtained in the first instance by Dr. Hayden, who brought home a few specimens only; next, Mr. F. C. A. Richardson placed in my hands a considerable collection;* and last summer my untiring friend Mr. F. C. Bowditch and myself spent several days working the shales. The mass of the specimens from this locality are irrecognizable, and those to the nature of which some clue can be obtained are generally fragmentary; wingless and often legless trunks are very common, and lead to the suggestion that the specimens had undergone long maceration in somewhat turbulent waters before final deposition. The zoological nature of the fauna will be fully considered at another time, and it need only be remarked now that one cannot avoid noticing the tropical aspect of the recognizable forms. More than eighty species are here enumerated. One or two only can be (doubtfully) referred to species described from the White River beds, † referred by Lesquereux to the same horizon. I must here express my indebtedness to Mr. G. D. Smith of Cambridge, who, with great liberality, has enabled me at all times to use his rich collections of Coleoptera, which chance to be specially valuable for my purpose from the intercalation of Mexican forms in the North American series. HYMENOPTERA. FORMICIDE. Lasius terreus.-A single specimen (No. 14692) obtained by Dr. Hayden at the "Petrified Fish Cut", Green River (alluded to in his Sun Pictures of Rocky Mountain Scenery, p. 98), is probably to be referred to this * See American Naturalist, vi, 665–668; Bulletin of this Survey, ii, No. 1, 77–87. + See Bulletin of this Survey, iii, No. 4, 741-762. Bull. iv. No. 4 -1 747 genus, but is in rather a poor state of preservation. The head is small and rounded, with antennæ shaped as in Lasius, but of which the number and relative length of the joints cannot be determined, from their obscurity; the long basal joint, however, appears to be comparatively short and uniform in size, being not quite so long as the width of the head, while the rest of the antennæ is more than half as long as the basal joint, and thickens very slightly toward the apex. The thorax, preserved so as to show more of a dorsal than a lateral view, is compact. oval, less than twice as long as broad, with no deep separation visible between the meso- and metathorax, tapering a little posteriorly. The peduncle, as preserved, is a minute, circular joint, but from its discolo ration appears to have had a regular, rounded, posterior eminence. The abdomen consists of five joints, is very short-oval, very compact and regular, and of about the size of the thorax, although rounder. The legs are long and slender, the femora of equal size throughout, and all the pairs similar. There is no sign of wings, and the specimen is prob ably a neuter. Length of body 7.5mm, of head 1.4mm, of thorax 3.2 mm, of abdomen 2.9mm; breadth of head 1.1mm, of thorax 1.9 mm, of abdomen 2.2; diameter of peduncle 0.55mm; length of first joint of antennæ 1mm, of rest of antennæ 1.65mm (?). MYRMICIDE. Myrmica sp.-A species of this family was found by Mr. Richardson (No. 53), but a specific name is withheld in the hope of finding better material on which to base it. The head is rather small, circular; the thorax very regularly ovate and nearly twice as long as broad; the peduncle small, and composed of two adjoining circular masses, the hinder slightly the larger; the abdomen is much broken, but evidently larger than the thorax and pretty plump; no appendages are preserved. Length of body 3.3mm; diameter of head 0.4mm; length of thorax 1.2; width of same 0.75mm; length of peduncle 0.25mm; diameter of anterior joint of same 0.1mm; width of abdomen 0.85mm, its probable length 1.8. BRACONIDÆ. Bracon laminarum.-A single specimen and its reverse (Nos. 4196,4197) show a body without wings or other appendages. The head is quadrate, broader than long, and nearly as broad as the thorax. The thorax is subquadrate, either extremity rounded, about half as long again as broad, the sides nearly parallel, and the surface, like that of the head. minutely granulated; abdomen fusiform, very regular, in the middle as broad as the thorax, as long as the head and thorax together, taper ing apically to a point, and composed apparently of six segments. Length of body 2.8mm, of head 0.6mm, of thorax 0.85mm, of abdomen 1.35; breadth of head 1.1mm, of thorax 1.2. CHALCIDIDE. Decatoma antiqua.—On the same stone (No. 4076) as Lystra Richardsoni, but at a slightly higher level, is a minute Chalcid fly. The wings are wanting, but the whole of the body is preserved, together with the antennæ. The head is large, arched, and otherwise well rounded, the face tapering below, the eyes large, deep, with their inner borders nearly parallel, leaving an equal front; the base of the antennæ cannot be made out, but beyond the long basal joint are six nearly equal quadrate joints, increasing very slightly indeed in size away from the head, scarcely so long as broad, the apical joint subconical, scarcely longer than the penultimate. Thorax compact, globose, minutely granulated, like the head; the abdomen also compact, arched, the tip rounded; beyond it, the ovipositor extends very slightly, apparently by pressure. On a stone collected by Mr. Richardson (No. 86) is pretty certainly another specimen of this species, in which the abdomen is distorted by pressure; the abdomen shows this by the rupture of the integument, and the result is an apparently slenderer abdomen; it is also a female, with exactly the same parts preserved, with the addition of the other antenna; but both antennæ are more obscure than in the other specimen, especially at the apex; they appear, however, to enlarge more rapidly, and may be clavate at the tip, in which case the insect cannot be the same. Length of body (of No. 4076) 1.85mm, of abdomen 0.95mm, of antennæ beyond basal joint 0.4mm; width of penultimate antennal joint 0.015mm. DIPTERA. CHIRONOMIDE. Chironomus sp.-A minute specimen (No. 141), apparently of this family, was taken by Mr. Richardson. Unfortunately, it has no wings, and little can be said of it, more than to record its occurrence; it is 3mm long, has large eyes, a stout thorax, and altogether resembles a Chironomus; it is, however, distinct from any found by Mr. Denton in the White River shales. TIPULIDE. Dicranomyia primitiva Scudd.-A single wingless male (No. 16), taken by Mr. Richardson, can be referred doubtfully to this species, originally described from White River. About fifteen other specimens of Tipulida were collected by Mr. Richardson, Mr. Bowditch, and myself at the same spot, but, unfor tunately, not one of them presents the vestige of a wing, and seldom anything more than the body; probably some of them also belong to the above-named species; others may with more doubt be referred to D. stigmosa Scudd.; but all are valueless for any precise determination, and, indeed, may not belong to Dicranomyia at all. MYCETOPHILIDE. Diadocidia? terricola.-This species is founded upon a single wing (No. 125) found by Mr. Richardson, differing to such a degree from Diadocidia that I only place it here because the only other reasonable course would be to refer it to a new genus, which would necessarily be con jectural, from the imperfection of the fragment. If a transverse vein exists in the middle of the wing, it must unite the fourth longitudinal vein with the second, and not, as in Diadocidia, with the third. The wing itself is shaped much as in Diadocidia, and, at least near its costal border, is covered with fine hairs arranged in rows parallel to the course of the neighboring veins; one of these rows in the costal cell is se distinct as to appear like a vein parallel to and lying within the auxi liary vein. The auxiliary vein terminates in the costal margin far beyond the middle of the wing, a feature apparently unknown in Mycetophilida; the first longitudinal vein terminates only a little further beyond, and, as in Diadocidia, there is no transverse vein connecting them; the second longitudinal vein terminates a little above the aper of the wing, curving downward at its extremity and apparently sur passed a little by the marginal vein; the third longitudinal vein origi nates from the second at only a short distance before the middle of the wing, and soon forks, or at about the middle of the wing; the fourth longitudinal vein is perhaps connected with the second at the point where it parts with the first by a cross vein perpendicular to the costa! margin; at least, it is elbowed at this point, its basal portion running. parallel to the costal margin, to the fifth longitudinal vein, which, beyond this point, has a gently sinuous course, and diverges rather strongly from the fourth; the sixth vein cannot be traced, although the axillary field is broad, very much as in Diadocidia, and the inner margin distinct. Probable length of wing 3.6mm; its breadth 1.45mm. Sackenia sp.-No. 7 of Mr. Richardson's collection represents a species of Mycetophilidæ apparently belonging to this genus, so far as can be determined. It closely resembles Sackenia arcuata Scudd. from the White River shales, but differs from it in its smaller size and in possess ing a proportionally larger and more arched thorax; the legs also appear to be shorter. Besides the body and (indistinctly) the antennæ and legs, only the upper portion of the wings remain, consisting of the costal margin and first and second longitudinal veins, with the cross vein uniting them; these wholly agree with the same features in S. are ata, excepting that the second longitudinal vein terminates a little higher up. Length of body 3.75m, of wings 2.9mm. Three other species of Mycetophilida occur among the specimens collected by Mr. Bowditch and myself, but they are indeterminable from their fragmentary condition. One of them, No. 4134, has indeed the remnant of a wing, but the portion of the venation preserved is only suf ficiently characteristic to enable us to judge that it belongs in this family. The thorax is strongly arched, and the full and tapering abdomen indicates a female; the head is gone; the thorax and abdomen are 3.5 long, and the wing probably 3mm long. Another of them, No. 4114, has a portion of the base of a wing, in which the forking of the fifth and sixth longitudinal veins is very close to the base, as in Sackenia, but nothing more can be said concerning it; the thorax is very globular and the abdomen short. Length of thorax and abdomen 3.65mm. The third species is represented by two specimens on one stone (No. 4205) which came from the buttes opposite Green River Station, and is the only fly which had the slightest value found in four days' search. One of the specimens is a pupa and the other an imago, apparently of the same species and distinct from either of the preceding, with a longer thorax and slenderer abdomen, provided with large ovate anal lobes. Length of thorax and abdomen 5mm. ASILIDE. Stenocinclis (arevós, xyzdís), nov. gen. This genus of Asilidæ is founded wholly upon characters drawn from the neuration of the wing, the only portion of the insect preserved. It falls into the group of Dasypogonina, in which the second longitudinal vein terminates in the margin apart from the first longitudinal vein, instead of uniting with it just before the margin. It is not very far removed from Dioctria, but differs from it and from all Asilide I have examined in that the third longitudinal vein arises from the first before the middle of the wing, instead of from the second longitudinal vein after its emission from the first; the first longitudinal vein has there fore two inferior shoots, giving the wing a very perlar argent, and causing it to differ radically from all other Asilida; indeed, it wood he hard to know where to look for a similar feature among a on Triphera unless it be in the atosalons groop of Cyrtide. The w124 very akty der, and all the cells 2-ally elongated, which also give as ge appearance. Stenocinclis anman-Ts werea ia pergerented by a wngatexz ment of a wing No. 44, wiles I found in the Green, Șt sag arada Nearly all the secration a preverede out the pomerica MALY A absent, and the length of the on a vaON accurately determined. The tART VAR AT GET" 7 amai slender wing. The mi ar 141 trn dater a q dle of the ecsta nanga: ne dra ang sad ve margin where the will. At th1 21 SAA, and lo que sóng sez. edge far toward the 1-0 1 |