46. On CROCODILUS ICENICUS (Seeley), a second and larger SPECIES of CROCODILE from the CAMBRIDGE UPPER GREENSAND, contained in the Woodwardian Museum of the University of Cambridge. By HARRY GOVIER SEELEY, Esq., F.L.S., F.G.S., &c., Professor of Geography in King's College, London. (Read June 21, 1876.)

IT is a curious coincidence that the evidence of the fossil now described, like that of Crocodilus cantabrigiensis, consists of one cervical and one dorsal vertebra. The vertebræ in this species, however, are associated; and their striking resemblance to existing Crocodiles had, I believe, already been recognized by Mr. Walter Keeping.

The centrum of the cervical vertebra is 24 inches long, and is divided from the neural arch by a rather deep suture, more than usually well marked by the neural arch projecting laterally a little beyond the centrum. In front the procœlous articulation is as deeply cupped as in any recent species. The cup is circular, about 1 inch in diameter; it was surrounded by a narrow border, now somewhat worn, so that the transverse diameter of the centrum, which was about 1 inch, cannot be exactly determined. Its depth appears to have been as great-though, as the small anterior hypapophysis is broken away, the depth as preserved is only 1 inch.

The neurapophyses are very strong. As they rise from the centrum they are directed outward and upward, constricted and rounded anteriorly above the centrum for the passage of the cervical nerve. The neurapophyses are constricted between the parapophyses and diapophyses, as well as between the diapophyses and zygapophyses. The least measurement of the neural arch from front to back is rather more than one inch.

The anterior zygapophysial facets are inclined at an angle of about 45° looking upward and inward; they measure about inch from front to back, and about 1 inch from below upward. Only that on the left side is preserved: it is smooth, its anterior margin hardly projects in front of the anterior face of the centrum, and its posterior margin is hardly behind the anterior margin of the diapophysis. The width between the anterior zygapophyses was about 2 inches. The inner margin of the facets of the zygapophyses descends below the top of the neural canal, which in front is subtriangular. As usual, there is an interspace between the facets, due to the neural spine being placed further backward; and from the middle of this area the vertical slightly elevated anterior margin of the neural spine arises. On the side of the neural arch the zygapophyses laterally curve downward and backward to the diapophyses, which project prominently. Above the diapophyses and behind the anterior zygapophyses the sides of the neural arch are considerably compressed, measuring 18 inch transversely at the shoulders of the

sides, where a concave area is terminated posteriorly by a ridge arising from the diapophysis; which runs upward and backward, presumably to the faces of the posterior zygapophyses, which are broken away.

The neural canal somewhat excavates the middle of the neural surface of the centrum. The posterior outlet of the neural canal appears formed of two pairs of sides a short pair below, converging to the middle of the centrum, and a long pair, 1 inch in length, converging upward and prolonged in the notch between the zygapophyses. The posterior aspect of the neural arch below the zygapophyses is flattened. The flattened surfaces are inch broad, and look obliquely outward and backward; they converge somewhat upward, and terminate inward in the rounded margin of the neural canal, upward in the posterior zygapophysial ridge, and outward and forward in the diapophyses. The length of the neural suture is 1 inch.

The neural spine appears to have been compressed, but is entirely broken away.

The diapophyses are obliquely ovate, inch long and inch deep; they are situate rather nearer the front than the middle of the side of the centrum. The transverse measurement through the diapophyses, as preserved, would be about 3 inches.

The lateral unarticular part of the centrum is about 1 inch long. Posterior to this region the centrum terminates in a large rounded articular ball, 13 inch wide, not quite so deep, and extending backward for fully inch. The greatest width of the centrum behind the posterior articulation is 13 inch.

The side of the centrum carries on its upper half, at less than half an inch behind the anterior articular margin and extending upward to the neural arch, the vertically ovate parapophysis, which as preserved is inch high and inch broad. Its lateral projection is probably but slightly worn. The width of the vertebra through the parapophyses is 1 inch.

The sides of the centrum below the parapophyses are slightly concave in length, somewhat flattened; and towards the middle of the base of the centrum they form a well rounded median surface, concave in length, which in the anterior half inch is prolonged downward into a small hypapophysis, now broken away.

The measurement from the rounded base of the centrum to the upper margin of the anterior zygapophyses is nearly 3 inches.

This vertebra is probably the last cervical. It differs from that of existing Crocodiles in the large size of the parapophyses, in the distinct anterior notch in the neural arch for the vertebral nerve, and the perfect convexity of the articular ball.

The dorsal vertebra has the centrum elongated, compressed from side to side, and well rounded on the under surface. It is 2 inches long, the lateral unarticular part being 13 inch, while the remainder is occupied by the well rounded, convex, posterior articular ball. The anterior cup is apparently circular, and measures 1 inch from side to side. The ball is 14 inch from side to side, and

has an aspect as though placed slightly below its proper position on the centrum; its external surface is rather concave behind the ball. The transverse diameter of the centrum at one inch from the posterior extremity is 1 inch. The neural suture is straight, 1 inch in length. The neural arch is remarkable for its length

and for the small extent to which it is notched in front and behind for the vertebral nerves, its least length being fully 1 inch. It rises vertically and continuously with the side of the centrum; and at a height of about 17 inch from the base of the centrum gives off the compressed transverse processes, which are almost entirely broken away. This process is continuous in front with the anterior zygapophysis, the articular facet of which is not horizontal, but looks a little inward as well as upward; the facets appear scarcely to project forward in front of the anterior articular margin. The transverse processes at the base, as preserved, have an antero-posterior measurement of 1 inch. Behind the process is a concave notch, posterior to which the postzygapophysis is produced; across the notches the measurement is 1 inch. There is a slight depression below the notch, bounded in front by a ridge directed outward and forward. As preserved, the transverse processes, which were horizontal, measure 24 inches from side to side. The neural arch was greatly compressed above the transverse platform. The neural spine is fractured at a height of less than 3 inches from the base of the centrum ; it measures 1 inch from front to back. The neural canal (which is obscured in front) appears to have been remarkably small; from side to side behind, the neural arch measured 1 inch.

This vertebra is the 6th or 7th dorsal. The depression of the posterior articular ball, and its perfect convexity, are the chief points in which it differs from existing species.

The remains indicate an animal about 16 feet long.

I have seen no other vertebrate fossil from a secondary stratum in which the bones preserved so closely resemble those of an existing type.

47. On MACRUROSAURUS SEMNUS (Seeley), a LONG TAILED ANIMAL with PROCELOUS VERTEBRE from the Cambridge Upper GREENSAND, preserved in the Woodwardian Museum of the University of Cambridge. By HARRY GOVIER SEELEY, Esq., F.L.S., F.G.S., &c., Professor of Geography in King's College, London. (Read June 21, 1876.)

ABOUT twelve years ago the Woodwardian Museum acquired from Mr. W. Farren a series of some 25 associated and successive caudal vertebræ, found at one of the deeper phosphatite washings on Coldham Common, Barnwell. At the same date, the Rev. W. Stokes Shaw, M.A., Caius College, obtained from a similar working at Barton, a locality a few miles westward, another associated series of 15 smaller vertebræ showing identical characters, and of such size as to exactly join on to the first series and complete the tail. These latter vertebræ, not improbably part of the same individual, being presented to the Museum, I arranged both sets in a continuous series. Very few appear to be missing in any part of the sequence, though the extremity of the tail is probably not preserved, and there are no means of estimating how many vertebræ may have intervened between the last of the sacral region and the earliest caudal which is preserved. The tail probably included 50 vertebræ, and may have reached a length of 15 feet, which would have amounted to one half the length of the animal if the proportions of modern crocodiles obtained. A few isolated vertebræ have also been collected; but no distinctive portions of the skeleton have come under my notice. The affinities of the animal are at present somewhat obscure; for the only available data from which a determination could be made are the following facts :-The articulation of the earlier vertebræ is procœlous; this character gradually changes till the articulations of the centrums are nearly flat; then they become biconcave, and towards the end of the tail are irregular. There are no chevron bones; and the centrum becomes elongated and rounded like a dice-box, after the pattern of Cetiosaurus and Lælaps. The neural arch in the greater and earlier part of the tail was supported on pedicles rising from the centrum; it was depressed, and devoid of neural spine.

The procœlous character in the caudal region has never before been recorded, so far as I remember, in combination with an absence of chevron bones in an animal of this size; and though the tail as a whole is more in harmony with the Lacertian type than with any other order of true Reptiles, yet we must look to future discoveries for evidence of the systematic position of the animal to which it belonged. In my Index to the Secondary Reptiles,' &c.*, I classed the animal doubtfully with the Dinosauria. If it is allowed

* Pp. xvii, 45.

to remain there, I do not see my way to placing it in any one of the subdivisions of that group.

The vertebræ are in different states of mineralization-some showing no indications of phosphatic infiltration, while in others this process has gone on to a considerable extent.

The preservation of the specimens is occasionally such that I cannot feel certain that all are arranged in exactly their true order of succession. The first vertebra preserved is an early caudal much decomposed on one side, and considerably abraded, with only the base of the neural arch preserved, and an indication of the anteroposterior extent of the fractured transverse process. Its imperfect preservation is due to the fact that the bone is open and cellular, and but slightly mineralized with phosphate of lime.

The articular surface of the centrum is deeply cupped anteriorly, and is more expanded in front than behind, where it forms a large hemispherical ball. The sides of the centrum are compressed, and converge towards the ventral surface, where they form a median rounded ridge. The length of the centrum is 8 inches, and of this the unarticular side of the centrum measures 5 inches; the depth from the neural canal to the base of the hinder part of the centrum, as preserved, is fully 5 inches, and in front was probably more. The side is smooth, with some longitudinal vascular impressions, gently concave from front to back. The basal keel is well rounded from side to side, and gently concave from front to back.

The transverse process appears to have been 34 inches in anteroposterior extent at its base, where fractured. It was strong. The neural canal was smooth and narrow.

What are probably pedicles for the neural arch extend to the anterior border of the cup. This process on the right side is compressed, less than half an inch thick, with an antero-posterior extent of 21 inches.

The worn fragment of the next vertebra is 7 inches long. On the third the transverse processes have disappeared. The anterior cup of this vertebra, as preserved, is 54 inches wide; and the centrum does not exceed that length; but the ball and the margin of the cup are both broken. The neural canal is more than an inch wide. On each side of it the centrum gives off strong compressed pedicles 2 inches in antero-posterior length, half an inch thick, inclined a little towards each other, and approaching to within half an inch of the anterior border, as preserved. These pedicles are not much more than half an inch high, and were probably separated from the neural arch by a horizontal suture.

The centrums now become rapidly smaller in diameter and flattened on the visceral surface. The articular cup remains as deeply marked; but the ball appears to have a depressed, flattened margin an inch wide around the elevated central boss, as in existing crocodiles. That numbered 8 is 6 inches long and has the cup 4 inches deep. No. 11 is 5 inches long, has the cup much less deep, but the ball is not at all preserved. The centrum has now acquired a dicebox form. No. 12 is as long, but the centrum is smaller, the cup