insect covered with long white hair. Winged individuals: Head and thorax black; abdomen black, except the margins and style, which are yellow. Nectaries a little longer than thick, yellowish, often slightly fuscous. Antennæ hairy; seventh joint filiform, almost as long as the three preceding taken together. Wings hyaline. Length 1.52mm; to tip of wings 2.54min

On young twigs and leaves of Salix lucida and S. babylonica. The venation of the wings is exceedingly variable; in one abnormal specimen I have observed a robust transverse vein running from the middle of the second discoidal to the base of the lower branch of the cubitus, thereby forming a closed trapezoidal cell.

CHAITOPHORUS SMITHIÆ, n. sp.-Winged form: General color dusky reddish. Wings hyaline; venation very variable. Nectaries two-thirds as long as the tarsi, vasiform, contracted at the base, expanding in the middle, and again contracted at the apex; the mouth flaring. Antennæ a little over half as long as the body, the third joint the longest, the fourth and fifth subequal, and the sixth joint two-thirds as long as the preceding. Seventh joint slender, very little longer than the preceding. Rostrum reaching the third pair of coxæ. Length 2.28mm; to tip of wings 4.56mm.

On leaves of Salix alba. May-June. Peoria, Ill. (Miss E. A. Smith). This species comes under Cladobius Koch, a genus which does not seem sufficiently distinct from Chaitophorus.

Though the shape of the nectaries is very remarkable, it seems to me scarcely sufficient to justify a generic separation.

CHAITOPHORUS QUERCICOLA, n. sp.-Apterous individuals: Dorsum greenish, with four rows of short tubercles, all of which, except a few in the side-rows, are black; their apical circumference with from three to five bristles; the two middle rows of tubercles stop at the head, but the two lateral rows are continued by smaller tubercles until near the base of the labrum. Rostrum reaching the second coxæ. Nectaries yellow, about as long as the tarsi, slightly enlarged at base, the mouth conspicuously flaring. Style not perceptible. Winged individuals: Antennæ very slightly pilose; fourth joint subequal to the fifth and two-thirds as long as the third joint; sixth about half as long as the preceding, and very little longer than the seventh. Wings with the stigma and veins much as in Ch. populicola; the veins lying in narrow dusky bands. Length of apterous individuals 1.52-2.02mm; length of wing 2.54mm.

On the under side of the leaf near the midrib. Quercus prinus. MayJune. Peoria, Ill. Of this interesting species, I have seen a number of apterous individuals, but only a single winged specimen, which was mounted on a slide kindly communicated by Miss E. A. Smith of Peoria, Ill. The dorsum of the winged individual is probably not tubercular, but this cannot be decided with certainty on account of the manner in which the specimen is mounted.

Though the antennæ of this species are not sufficiently pilose to justify its being placed in Chaitophorus, its general appearance seems to point to this as its rightful position.

Art. II.-The Relations of the Horizons of Extinct Vertebrata of Europe and North America.

By E. D. Cope.

The history of the succession of life upon any one portion of the earth's surface is replete with matter for speculation. It shows us a series of faunæ succeeding each other, each of which, in many instances, commences without previous announcement in the forms of older periods, and disappears without leaving representatives in later ones. With this basis of fact, which naturally enough has been furnished by the longest explored and best known portion of the earth, Europe, we turn to other lands with the hope of obtaining further light upon a subject so full of mystery. These types of life, did they originate in a single centre, from which they disseminated themselves? and, if so, did each form originate in a region of its own or not? Or, did the same types of generic structure appear at different points on the earth's surface independently; and, if so, whether cotemporaneously, or at different times?

For a solution of these and similar questions, we naturally look to a comparison of the facts first established, with those obtained more recently by exploration in other regions. In this quest, no portion of the earth offers greater promise of results than America. As the second great continent, separated from the other by the greatest possible water surface, we anticipate the widest diversity in the character of its life-history. If the types of life have originated independently, we will find evidenceof it by studying American palæontology; if their origin has been through gradual modification, America should furnish us with many intermediate faunæ.

The identification of the generic types of North American Vertebrata has now advanced to a point which renders such a comparison possible. Although the subject is in its infancy, the following pages will show that an important contribution to it can be now made. The comparisons instituted in this paper commence with the coal-measures, and with the Batrachia of that period. As regards the palæozoic fishes, I have not yet devoted that attention to them which is necessary for their discussion, and I refer to the papers of Newberry for several important identifications of genera as common to the two continents.

The structure of the Batrachia of the coal-measures is not yet sufficiently well known to enable the most exact comparisons to be made, but close parallels, if not identities, of genera exist. Such are the

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Oëstocephalus and Ceraterpeton of Ohio as compared with the Urocordylus and Ceraterpeton of Great Britain.

The Permian vertebrate fauna which I discovered in Illinois and Texas, exhibits close parallels, but not yet generic identity, in the two continents. Thus, the American Clepsydrops and Dimetrodon are near to the Deuterosaurus of Perm in Russia, and the Lycosaurus of the mountains of South Africa. The Texan genus Pariotichus may, with further information, prove to be identical with Procolophon Ow. from the Tafelberg. Humeri of the type discovered by Kutorga in Russia, and by Owen in South Africa, are found in North America, and the same remarkable type has been recently discovered by Gaudry in France. The peculiar type of Labyrinthodont vertebræ described by me under the genus Rhachitomus from Texas has been discovered by Gaudry in France. The present indications are that close similarity between the fauna of this period in Europe and America will be discovered. Nevertheless, up to the present time no representatives of the striking American forms Diadectes, Bolosaurus, Empedocles, and Cricotus. have yet been found in any other continent.

As regards the Triassic fauna, it differs from that of the Permian in being better known in Europe than America. As marine Trias is little developed in North America, so the vertebrate fauna of the Muschelkalk has not been discovered in the latter country. It is otherwise with the Keuper. The characteristic genus of that epoch, Belodon, existed in America, and parallels, if not identity, exist in the genera Thecodontosaurus and Palæosaurus. These are known in America from teeth only. The reptiles are accompanied in North America, as in Europe, by Stegocephalous Batrachia, mostly Labyrinthodonts, but their generic affinities are yet unknown.

The great Jurassic faunæ are as yet but sparsely represented in North American palæontology. The marine Vertebrata of the Lias are either unknown or are represented by a few provisional identifications of unsatisfactory fragments. We do not yet know any deposits in North America which contain the typical reptilian genera Plesiosaurus, Ichthyosaurus, Pliosaurus, and Dimorphodon, or the fishes of the Dapediida. This formation, so important in Europe, is almost omitted from the North American series. A few more characteristic fossils of the Rocky Mountain region represent the Oölite, particularly the Upper Oölite, while Teleosaurus and Steneosaurus, and their allies, are not yet known from North American beds. Strata said to be included in the Dakota (which on the evidence of plants and invertebrate fossils has been placed at the bottom of the Cretaceous series) have produced a genus not yet distinguishable from Megalosaurus. This genus has not been identified beyond doubt from above the Oölite in England. From the same beds in the Rocky Mountain region come genera which nearly resemble the one from the English Oölite (Forest Marble) called by Phillips, Cetiosaurus, and the genus from the Oxfordian of Honfleur, called by von Meyer,

Streptospondylus. Beyond this no comparisons can be made, and we therefore pass to the rich fauna of the Kimmeridge. North America cannot show such records of this epoch as have been found in Europe. There are no Archaeopteryx, Rhamphorhynchus, nor Pterodactylus; no Leptolepis, Thrissops, nor other of the numerous fishes of Solenhofen. The Omosaurus has, however, some very close relatives in the supposed Dakota beds of the Rocky Mountains. No remains of that primitive Marsupial fauna which occurs in the Purbeck have yet been detected in the Western Continent. A partial representation of the Wealden fauna of Europe is found in the beds of the Rocky Mountains mingled with the types of the Oölite and Kimmeridge already mentioned. The relationships of this fauna to those of the European Jurassic series may be thus exhibited:

From the above table it will be seen how difficult it is at the present to parallelize the related beds of the Jurassic periods of the two continents at the present time. All that can be said is that many types resembling nearly those of different horizons of the European Jurassic are found to have lived together or near together in the Rocky Mountain region of North America.

That the Cretaceous fauna of North America was the richest in the cold-blooded Vertebrata is indicated by the present state of discovery. The ocean of the interior of the continent deepened from the beginning * Chondrosteosaurus Owen.

+ Iguanodon prœcursor Sauv.

A near affinity has been shown by Professor Owen to exist between Eucamerotus and Camarasaurus. Professor Owen believes these genera to be identical; but the neural spines of the anterior dorsal vertebræ are very different, being single in the former, and double in the latter.

of the period until the epoch of the Niobrara, and then gradually shallowed until the elevations of the bottom began to divide the waters. The closing scenes of this great period were enacted amid a labyrinth of lagoons and lakes of brackish and fresh water, whose deposits form the beds of the Laramie epoch.

The fauna of the deep-sea epoch, the Niobrara, is the best known. Here the remains of Pythonomorpha constitute its prevailing characteristic, while Elasmosaurus and Polycotylus, with but few species, represent the numerous Sauropterygia of Europe. Crocodiles were apparently wanting, while turtles and a peculiar group of Pterosauria were only moderately abundant. The fish fauna was very rich and varied. Here the Saurodontida, like the Molluscous family of the Rudistes, appeared, and as soon disappeared, accompanied by the peculiar form, Erisichthe, and the family of Stratodontidæ. The genera of Mount Lebanon, Leptotrachelus and Spaniodon, occur in this bed in Dakota; but the closest parallelism is exhibited with the Lower Chalk or Turonian of Western Europe. The general facies of the reptilian fauna is that of the Lower Chalk, and there is little doubt that several genera are identical in the two continents, e. g. Elasmosaurus. The apparent peculiarity of the Chalk in America is the abundance of forms (four genera) of Pythonomorpha with numerous species, while but two genera have yet been found in Europe, and the presence of birds, with biconcave vertebræ, and teeth. This interesting type, which was first discovered by Seeley in the genus named by him Enaliornis, and afterwards found by Marsh to possess teeth, has been found at a lower horizon in England, the Upper Greensand. But in England, France, and Westphalia occur the genera of fishes above mentioned, as Portheus, Ichthyodectes, Saurodon, Saurocephalus, Erisichthe, Empo, Pachyrhizodus, Enchodus, Leptotrachelus, etc. This close relationship of the horizons permits an identification, and it is the first instance which appears to me to be susceptible of satisfactory demonstration.

The next horizon of the Cretaceous which has yielded many vertebrate remains in North America is the Fox Hills formation (including the Fort Pierre bed). Here the genus Mosasaurus appears in America, and is accompanied by the earliest crocodiles with procœlous vertebræ, and by numerous marine turtles which partake of the characters of both Chelydride and Cheloniida, which I have called the Propleurida. Beryx appears first here in America. The predominant genus of fishes is Enchodus, and the principal Dinosauria are Lælaps and Hadrosaurus. This horizon has been parallelized with the Maestricht of Europe, and several genera are common to the two beds; such are Mosasaurus and Enchodus. The genus Hadrosaurus, and the family of turtles I have called the Adocida, remain undiscovered in Europe; hence the identity of faunæ cannot be established.

The lacustrine beds, or summit of the American Cretaceous series, the Laramie of Hayden, present the remains of a populous fauna and a rich