CHAPTER XIII

ANCIENT ORNITHOSAURS FROM THE LIAS

Sir Richard Owen after some time separated the fossil as a distinct genus, named Dimorphodon; for it was in many ways unlike the Pterodactyles described from Bavaria. The name Dimorphodon indicated the two distinct kinds of teeth in the jaws, a character which is still unparalleled among Pterodactyles of newer age. There are a few large pointed, piercing and tearing teeth in the front of the jaws, with smaller teeth further back, placed among the tearing teeth in the upper jaw; while in the lower jaw the small teeth are continuous, close-set, and form a fine cutting edge like a saw.

The Dimorphodon has a short beak, a deep head, and deep lower jaw, which is overlapped by the cheek bones. The side of the head is occupied by four vacuities, separated by narrow bars of bone. First, in front, is the immense opening for the nostril, triangular in form, with the long upper side following the rounded curve of the face. A large triangular opening intervenes between the nose hole and the eye hole, scarcely smaller than the former, but much larger than the orbit of the eye. The eye hole is shaped like a kite or inverted pear. Further back still is a narrower vertical opening known as the lateral or inferior temporal vacuity. The back of the head is badly preserved. The two principal skulls differ in depth, probably from the strains under which they were pressed flat in the clay. A singular detail of structure is found in the extremity of the lower jaw, which is turned slightly downward, and terminates in a short toothless point. The head of Dimorphodon is about eight inches long.

The extreme length of the animal from the tip of the nose to the end of the tail may have been 3 feet 4 inches, supposing it to have walked on all fours in the manner of a Reptile or Mammal. This may have been a common position, but Dimorphodon may probably also have been a biped. Before 1875, when the first restoration appeared in the Illustrated London News, the legs had been regarded as too short to have supported the animal, standing upon its hind limbs. They are here seen to be well adapted for such a purpose. The upper leg bone is 3¼ inches long, the lower leg bone is 4½ inches long, and the singularly strong instep bones are firmly packed together side by side as in a leaping or jumping Mammal, and measure 1½ inches in length. Dimorphodon differs from several other Pterodactyles in having the hind limb provided with a fifth outermost short instep bone, to which two toe bones are attached. These bones are elongated in a way that may be compared, on a small scale, with the elongation of the wing finger in the fore limb. The digit was manifestly used in the same way as the wing finger, in partial support of a flying membrane, though its direction may have been upward and outward, rather than inward. There is no evidence of a pulley joint between the metatarsal and the adjacent phalange.

The height of the Dimorphodon, standing on its hind legs in the position of a Bird, with the wings folded upon the body in the manner of a Bird, was about 20 inches. An ungainly, ill-balanced animal in aspect, but not more so than many big-headed birds, and probably capable of resting upon the instep bones as many birds do. The chief point of variation from the Pterodactyle wing is in the relative length of the metacarpus in Dimorphodon. It is shorter than the other bones in the wing, never exceeding 1½ inches. The total length of all the arm bones down to the point where the metacarpus might have touched the ground, or where the wing finger is bent upon it, is about 9 inches, which gives a length of less than 6 inches below the upper arm bone. The four bones of the wing finger measure, from the point where the first bone bends upon the metacarpus, less than 18 inches. So that the wings could only have been carried in the manner of the wings of a Bat, folded at the side and directed obliquely over the back when the animal moved on all fours. Its body would appear to have been raised high above the ground, in a manner almost unparalleled in Reptiles, and comparable to Birds and Mammals. Dimorphodon is to be imagined in full flight, with the body extended like that of a Bird, when the wings would have had a spread from side to side of about 4 feet 4 inches. As in other animals of this group, the three claws on the front feet are larger than the similar four claws on the hind feet; as though the fingers might have functions in grasping prey, which were not shared by the toes.

The restorations give faithful pictures of the skeleton, and the form of the body is built upon the indications of muscular structure seen in the bones.

A second English Pterodactyle is found in the Upper Lias of Whitby. It is only known from an imperfect skull, published in 1888. It has the great advantage of preserving the bones in their natural relations to each other, and with a length of head probably similar to Dimorphodon shows that the depth at the back of the eye was much less; and the skull wants the arched contour of face seen in Dimorphodon. The head has the same four lateral vacuities, but the nostril is relatively small and elongated, extending partly above the oval antorbital opening, which was larger. There is thus a difference of proportion, but it is precisely such as might result from the species having the skull flatter. The head is easily distinguished by the small nostril, which is smaller than the orbit of the eye. The animal is referred to another genus. The quadrate bones which give attachment to the lower jaw send a process inward to meet the bones of the palate, which differ somewhat from the usual condition. Two bony rods extend from the quadrate bones backward and upward to the sphenoid, and two more slender bones extend from the quadrate bones forward, and converge in a V-shape, to define the division between the openings of the nostrils on the palate. The V-shaped bone in front is called the vomer, while the hinder part is called pterygoid. The bones that extend backward to the sphenoid are not easily identified. This animal is one of the most interesting of Pterodactyles from the very reptilian character exhibited in the back of the head, which appears to be different from other specimens, which are more like a bird in that region. Yet underneath this reptilian aspect, with the bony bar at the side of the temporal region of the head formed by the squamosal and quadrate bones, defining the two temporal vacuities as in Reptiles, a mould is preserved of the cavity once occupied by the brain, showing the chief details of structure of that organ, and proving that in so far as it departs from the brain of a Bird it appears to resemble the brain of a Mammal, and is unlike the brain of a Reptile.

The Pterodactyles from the Lias of Germany are similar to the English types, in so far as they can be compared. In 1878 I had the opportunity of studying those which were preserved in the Castle at Banz, which Professor Andreas Wagner, in 1860, referred to the new genus Dorygnathus. The skull is unknown, but the lower jaw, 6½ inches long, is less than 2½ inches wide at the articulation with the quadrate bone in the skull. The depth of the lower jaw does not exceed ¼ inch, so that it is in marked contrast to Buckland's Dimorphodon. The symphysis, which completely blends the rami of the jaw, is short. As far as it extends it contains large tearing teeth, followed by smaller teeth behind, like those of Dimorphodon. But this German fossil appears to differ from the English type in having the front of the lower jaw, for about ¾ inch, compressed from side to side into a sharp blade or spear, more marked than in any other Pterodactyle, and directed upward instead of downward as in Dimorphodon. Nearly all the measurements in the skeleton are practically identical with those of the English Dimorphodon, and extend to the jaw, humerus, ulna and radius, wing metacarpal, first phalange of the wing finger. The principal bones of the hind limb appear to be a little shorter; but the scapula and coracoid are slightly larger. All these bones are so similar in form to Dimorphodon that they could not be separated from the Lyme Regis species, if they were found in the same locality.

Just as the Upper Lias in England has yielded a second Pterodactyle, so the Upper Lias in Germany has yielded a skeleton, to which Felix Plieninger, in 1894, gave the name Campylognathus. It is an instructive skeleton, with the head much smaller than in Dimorphodon, being less than 6 inches long, but, unfortunately, broken and disturbed. A lower jaw gives the length 4½ inches. Like the other Pterodactyles from the Lias, it has the extremity of the beak toothless, with larger teeth in the region of the symphysis in front and smaller teeth behind. The jaw is deeper than in the Banz specimen from the Lower Lias, but not so deep as in Dimorphodon. The teeth of the upper jaw vary in size, and there appears to be an exceptionally large tooth in the position of the Mammalian canine at the junction of the bones named maxillary and intermaxillary.

The nasal opening is small and elongated, as in the English specimen from Whitby. As in that type there is little or no indication of the convex contour of the face seen in Dimorphodon.

The neck does not appear to be preserved. In the back the vertebræ are about ³/₁₀ inch long, so that twelve, which is the usual number, would only occupy a length of a little more than 3½ inches. The tail is elongated like that of Dimorphodon, and bordered in the same way by ossified ligaments. There are thirty-five tail vertebræ. Those which immediately follow the pelvis are short, like the vertebræ of the back. But they soon elongate, and reach a maximum length of nearly 1½ inches at the eighth, and then gradually diminish till the last scarcely exceeds ¹/₈ inch in length. The length of the tail is about 22 inches; this appears to be an inch or two longer than in Dimorphodon. The longest rib measures 2½ inches, and the shortest 2 inches. These ribs probably were connected with the sternum, which is imperfectly preserved.

The bones of the limbs have about the same length as those of Dimorphodon, so far as they can be compared, except that the ulna and radius are shorter. The wing metacarpal is of about the same length, but the first phalange of the wing finger measures 6¼ inches, the second is about 8¼ inches, the third 6½ inches, and the fourth 4¾ inches; so that the total length of the wing finger was about half an inch short of 2 feet. One character especially deserves attention in the apparent successive elongation of the first three phalanges in the wing finger in Dimorphodon. The third phalange is the longest in the only specimen in which the finger bones are all preserved. Usually the first phalange is much longer than the second, so that it is a further point of interest to find that this German type shares with Dimorphodon a character of the wing finger which distinguishes both from some members of the group by its short first phalange.

The pelvis is exceptionally strong in Campylognathus, and although it is crushed the bones manifestly met at the base of the ischium, while the pubic bones were separated from each other in front. The bones of the hind limb are altogether shorter in the German fossil than in Dimorphodon, especially in the tibia; but the structure of the metatarsus is just the same, even to the short fifth metatarsal with its two digits, only those bones are extremely short, instead of being elongated as in Dimorphodon. It is therefore convenient, from the different proportions of the body, that Campylognathus may be separated from Dimorphodon; but so much as is preserved of the English specimen from the Upper Lias of Whitby rather favours the belief that our species should also be referred to Campylognathus, which had not been figured when the Whitby skull was referred to Scaphognathus by Mr. Newton. It may be doubtful whether there is sufficient evidence to establish the distinctness of the other German genus Dorygnathus, though it may be retained pending further knowledge.

In these characters are grounds for placing the Lias Pterodactyles in a distinct family, the Dimorphodontidæ, as was suggested in 1870. This evidence is found in the five metatarsal bones, of which four are in close contact, the middle two being slightly the longest, so as to present the general aspect of the corresponding bones in a Mammal rather than a Bird. Secondly, the very slender fibula, prolonged down the length of the shin bone, which ends in a rounded pulley like the corresponding bone of a Bird. Thirdly, the great elongation of the third wing phalange. Fourthly, the prolongation of the coracoid bone beyond the articulation for the humerus, as in a Bird. And the toothless, spear-shaped beak, and jaw with large teeth in front and small teeth behind, are also distinctive characters.

CHAPTER XIV

ORNITHOSAURS FROM THE MIDDLE SECONDARY ROCKS

The Stonesfield Slate in England, which corresponds in age with the lower part of the Great or Bath Oolite, yields many evidences of terrestrial life—land plants, insects, and mammals—preserved in a marine deposit. A number of isolated bones have been found of Pterodactyles, some of them indicating animals of considerable size and strength. The nature of the limestone was unfavourable to the preservation of soft wing membranes, or even to the bones remaining in natural association. Very little is known of the head of Rhamphocephalus. One imperfect specimen shows a long temporal region which is wide, and a very narrow interspace between the orbits; with a long face, indicated by the extension of narrow nasal bones. The lower jaw has an edentulous beak or spear in front, which is compressed from side to side in the manner of the Liassic forms, but turned upward slightly, as in Dorygnathus or Campylognathus. Behind this extremity are sharp, tall teeth, few in number, which somewhat diminish in size as they extend backward, and do not suddenly change to smaller series, as in the Lias genera. A few small vertebræ have been found, indicating the neck and back. The sacrum consists of five vertebræ. One small example has a length of only an inch. It is a little narrower behind than in front, and would be consistent with the animal having had a long tail, which I believe to have been present, although I have not seen any caudal vertebræ. The early ribs are like the early ribs of a Crocodile or Bird in the well-marked double articulation. The later ribs appear to have but one head. V-shaped abdominal ribs are preserved. Much of the animal is unknown. The coracoid seems to have been directed forward, and, as in a bird, it is 2½ inches long. The humerus is 3½ inches long, and the fore-arm measured 6 inches, so that it was relatively longer than in Dimorphodon. The metacarpus is 1¾ inches long. The wing finger was exceptionally long and strong. Professor Huxley gave its length at 29 inches. My own studies lead to the conclusion that the first finger bone of the wing was the shorter, and that although they did not differ greatly in length, the second was probably the longest, as in Campylognathus.

Professor Huxley makes the second and third phalanges 7¾ inches long, and the first only about ³/₈ inch shorter, while the fourth phalange is 6½ inches. These measurements are based upon some specimens in the Oxford University Museum. There is only one first phalange which has a length of 7¾ inches. The others are between 5 and 6 inches, or but little exceed 4 inches; so that as all the fourth phalanges which are known have a length of 6½ inches, it is possible that the normal length of the first phalange in the larger species was 5½ inches. The largest of the phalanges which may be classed as second or third is 8½ inches, and that, I suppose, may have been associated with the 7¾ inches first phalange. But the other bones which could have had this position all measure 5½ and 7¾ inches. The three species indicated by finger bones may have had the measurements:—

The femur is represented by many examples—one 3¾ inches long, and others less than 3 inches long (2⁹/₁₀). In Campylognathus, which has so much in common with the jaw and the wing bones in size, the upper leg bone is 2⁸/₁₀ inches. Therefore if we assign the larger femur to the larger wing, the femur will be relatively longer in all species of Rhamphocephalus than in Campylognathus. Only one example of a tibia is preserved. It is 3½ inches long, or only ¹/₁₀ inch shorter than the bone in Campylognathus, which has the femur 2⁸/₁₀ inches, so that I refer the tibia of Rhamphocephalus to the species which has the intermediate length of wing. These coincidences with Campylognathus establish a close affinity, and may raise the question whether the Upper Lias species may not be included in the Stonesfield Slate genus Rhamphocephalus.

The late Professor Phillips, in his Geology of Oxford, attempted a restoration of the Stonesfield Ornithosaur, and produced a picturesque effect (p. 164); but no restoration is possible without such attention to the proportions of the bones as we have indicated.

OXFORD CLAY

A few bones of flying reptiles have been found in the Lower Oxford Clay near Peterborough, and others in the Upper Oxford Clay at St. Ives, in Huntingdonshire. A single tail vertebra from the Middle Oxford Clay, near Oxford, long since came under my own notice, and shows that these animals belong to a long-tailed type like Campylognathus. The cervical vertebræ are remarkable for being scarcely longer than the dorsal vertebræ; and the dorsal are at least half as long again as is usual, having rather the proportion of bones in the back of a crocodile.

LITHOGRAPHIC SLATE

Long-tailed Pterodactyles are beautifully preserved in the Lithographic Limestone of the south of Bavaria, at Solenhofen, and the quarries in its neighbourhood, often with the skeleton or a large part of it flattened out in the plane of bedding of the rock. Fine skeletons are preserved in the superb museum at Munich, at Heidelberg, Bonn, Haarlem, and London, and are all referred to the genus Rhamphorhynchus or to Scaphognathus. It is a type with powerfully developed wings and a long, stiff tail, very similar to that of Dimorphodon, so that some naturalists refer both to the same family. There is some resemblance.

The type which is most like Dimorphodon is the celebrated fossil at Bonn, sometimes called Pterodactylus crassirostris, which in a restored form, with a short tail, has been reproduced in many text-books. No tail is preserved in the slab, and I ventured to give the animal a tail for the first time in a restoration (p. 163) published by the Illustrated London News in 1875, which accompanied a report of a Royal Institution lecture. Afterwards, in 1882, Professor Zittel, of Munich, published the same conclusion. The reason for restoring the tail was that the animal had the head constructed in the same way as Pterodactyles with a long tail, and showed differences from types in which the tail is short; and there is no known short-tailed Pterodactyle, with wrist and hand bones, such as characterise this animal. The side of the face has a general resemblance to the Pterodactyles from the Lias, for although the framework is firmer, the four apertures in the head are similarly placed. The nostril is rather small and elongated, and ascends over the larger antorbital vacuity. The orbit for the eye is the largest opening in the head, so that these three apertures successively increase in size, and are followed by the vertically elongated post-orbital vacuity. The teeth are widely spaced apart, and those in the skull extend some distance backward to the end of the maxillary bone. There are few teeth in the lower jaw, and they correspond to the large anterior teeth of Dimorphodon, there being no teeth behind the nasal opening. The lower jaw is straight, and the extremities of the jaws met when the mouth was closed. The breast bone does not show the keel which is so remarkable in Rhamphorhynchus, which may be attributed to its under side being exposed, so as to exhibit the pneumatic foramina.

The ribs have double heads, more like those of a Crocodile in the region of the back than is the case with the bird-like ribs from Stonesfield. The second joint in the wing finger may be longer than the first—a character which would tend to the association of this Pterodactyle with species from the Lias; a relation to which attention was first drawn by Mr. E. T. Newton, who described the Whitby skull.

The Pterodactyles from the Solenhofen Slate which possess long tails have a series of characters which show affinity with the other long-tailed types. The jaws are much more slender. The orbit of the eye in Rhamphorhynchus is enormously large, and placed vertically above the articulation for the lower jaw. Immediately in front of the eye are two small and elongated openings, the hinder of which, known as the antorbital vacuity, is often slightly smaller than the nostril, which is placed in the middle length of the head, or a little further back, giving a long dagger-shaped jaw, which terminates in a toothless spear. The lower jaw has a corresponding sharp extremity. The teeth are directed forward in a way that is quite exceptional. Notwithstanding the massiveness and elongation of the neck vertebræ, which are nearly twice as long as those of the back, the neck is sometimes only about half the length of the skull.

All these long-tailed species from the Lithographic Stone agree in having the sternum broad, with a long strong keel, extending far forward. The coracoid bones extend outward like those of a Crocodile, so as to widen the chest cavity instead of being carried forward as the bones are in Birds. These bones in this animal were attached to the anterior extremity of the sternum, so that the keel extended in advance of the articulation as in other Pterodactyles. The breadth of the sternum shows that, as in Mammals, the fore part of the body must have been fully twice the width of the region of the hip-girdle, where the slenderer hind limbs were attached. The length of the fore limb was enormous, for although the head suggests an immense length relatively to the body, nearly equal to neck and back together, the head is not more than a third of the length of the wing bones. The wing bones are remarkable for the short powerful humerus with an expanded radial crest, which is fully equal in width to half the length of the bone. Another character is the extreme shortness of the metacarpus, usually associated with immense strength of the wing metacarpal bone.

The hind limbs are relatively small and relatively short. The femur is usually shorter than the humerus, and the tibia is much shorter than the ulna. The bones of the instep, instead of being held together firmly as in the Lias genera, diverge from each other, widening out, though it often happens that four of the five metatarsals differ but little in length. The fifth digit is always shorter.

The hip-girdle of bones differs chiefly from other types in the way in which those bones, which have sometimes been likened to the marsupial bones, are conditioned. They may be a pair of triangular bones which meet in the middle line, so that there is an outer angle like the arm of a capital Y. Sometimes these triangular bones are blended into a curved, bow-shaped arch, which in several specimens appears to extend forward from near the place of articulation of the femur. This is seen in fossil skeletons at Heidelberg and Munich. It is possible that this position is an accident of preservation, and that the prepubic bones are really attached to the lower border of the pubic bones.

Immense as the length of the tail appears to be, exceeding the skull and remainder of the vertebral column, it falls far short of the combined length of the phalanges of the wing finger. The power of flight was manifestly greater in Rhamphorhynchus than in other members of the group, and all the modifications of the skeleton tend towards adaptation of the animals for flying. The most remarkable modification of structure at the extremity of the tail was made known by Professor Marsh in a vertical, leaf-like expansion in this genus, which had not previously been observed (p. 161). The vertebræ go on steadily diminishing in length in the usual way, and then the ossified structures which bordered the tail bones and run parallel with the vertebræ in all the Rhamphorhynchus family, suddenly diverge downward and upward at right angles to the vertebræ, forming a vertical crest above and a corresponding keel below; and between these structures, which are identified with the neural spines and chevron bones of ordinary vertebræ, the membrane extends, giving the extremity of the tail a rudder-like feature, which, from knowledge of the construction of the tail of a child's kite, may well be thought to have had influence in directing and steadying the animal's movements. There are many minor features in the shoulder-girdle, which show that the coracoid, for example, was becoming unlike that bone in the Lias, though it still continues to have a bony union with the elongated shoulder-blade of the back.

The great German delineator of these animals, Von Meyer, admitted six different species. Mr. Newton and Mr. Lydekker diminish the number to four. It is not easy to determine these differences, or to say how far the differences observed in the bones characterise species or genera. It is certain that there is one remarkable difference from other and older Pterodactyles, in that the last or fourth bone in the wing finger is usually slightly longer than the third bone, which precedes it. There is a certain variability in the specimens which makes discussion of their characters difficult, and has led to some forms being regarded as varieties, while others, of which less material is available, are classed as species. I am disposed to say that some of the confusion may have resulted from specimens being wrongly named. Thus, there is a Rhamphorhynchus called curtimanus, or the form with the short hand. It is represented by two types. One of these appears to have the humerus short, the ulna and radius long, and the finger bones long; the other has the humerus longer, the ulna much shorter, and the finger bones shorter. They are clearly different species, but the second variety agrees in almost every detail with a species named hirundinaceus, the swallow-like Rhamphorhynchus. This identification shows, not that the latter is a bad species, but that curtimanus is a distinct species which had sometimes been confounded with the other. While most of these specimens show a small but steady decrease in the length of the several wing finger bones, the species called Gemmingi has the first three bones absolutely equal and shorter than in the species curtimanus, longimanus, or hirundinaceus. In the same way, on the evidence of facts, I find myself unable to join in discarding Professor Marsh's species phyllurus, on account of the different proportions of its limb bones. The humerus, metacarpus, and third phalange of the wing finger in Rhamphorhynchus phyllurus are exceptionally short as compared with other species. Everyone agrees that the species called longicaudus is a distinct one, so that it is chiefly in slight differences in the proportions of constituent parts of the skeleton that the types of the Rhamphorhynchus are distinguished from each other. I cannot quite concur with either Professor Zittel (Fig. 58, 3) or Professor Marsh (Fig. 58, 2) in the expansion which they give to the wing membrane in their restorations; for although Professor Zittel represents the tail as free from the hind legs, while Professor Marsh connects them together, they both concur in carrying the wing membrane from the tip of the wing finger down to the extremity of the ankle joint. I should have preferred to carry it no further down the body than the lower part of the back, there being no fossil evidence in favour of this extension so far as specimens have been described. Neither the membranous wings figured by Zittel nor by Marsh would warrant so much body membrane as the Rhamphorhynchus has been credited with. I have based my restoration (p. 161) of the skeleton chiefly on Rhamphorhynchus phyllurus.

The Pterodactylia are less variable; and the variation among the species is chiefly confined to relative length of the head, length of the neck, and the height of the body above the ground. The tail is always so short as to be inappreciable. Many of the specimens are fragmentary, and the characters of the group are not easily determined without careful comparisons and measurements. The bones of the fore limb and wing finger are less stout than in the Rhamphorhynchus type, while the femur is generally a little longer than the humerus, and the wing finger is short in comparison with its condition in Rhamphorhynchus. These short-tailed Pterodactyles give the impression of being active little animals, having very much the aspect of birds, upon four legs or two. The neck is about as long as the lower jaw, the antorbital vacuity in the head is imperfectly separated from the much larger nasal opening, the orbit of the eye is large and far back, the teeth are entirely in front of the nasal aperture, and the post-orbital vacuity is minute and inconspicuous. The sternum is much wider than long, and no specimens give evidence of a manubrium. The finger bones progressively decrease in length. The prepubic bones have a partially expanded fan-like form, and never show the triradiate shape, and are never anchylosed. About fifteen different kinds of Pterodactyles have been described from the Solenhofen Slate, mostly referred to the genus Pterodactylus, which comprises forms with a large head and long snout. Some have been placed in a genus (Ornithocephalus, or Ptenodracon) in which the head is relatively short. The majority of the species are relatively small. The skull in Ornithocephalus brevirostris is only 1 inch long, and the animal could not have stood more than 1½ inches to its back standing on all fours, and but little over 2½ inches standing as a biped, on the hind limbs.

A restoration of the species called Pterodactylus scolopaciceps, published in 1875 in the Illustrated London News in the position of a quadruped, shows an animal a little larger, with a body 2½ inches high and 6 to 7 inches long, with the wing finger 4½ inches long. Larger animals occur in the same deposit, and in one named Pterodactylus grandis the leg bones are a foot long; and such an animal may have been nearly a foot in height to its back, standing as a quadruped, though most of these animals had the neck flexible and capable of being raised like the neck of a Goose or a Deer (p. 30), and bent down like a Duck's when feeding.

The type of the genus Pterodactylus is the form originally described by Cuvier as Pterodactylus longirostris (p. 28). It is also known as P. antiquus, that name having been given by a German naturalist after Cuvier had invented the genus, and before he had named the species. There are some remarkable features in which Cuvier's animal is distinct from others which have been referred to the same genus. Thus the head is 4½ inches long, while the entire length of the backbone to the extremity of the tail is only 6½ inches, and one vertebra in the neck is at least as long as six in the back, so that the animal has the greater part of its length in the head and neck, although the neck includes so few vertebræ. Nearly all the teeth—which are few in number, short and broad, not exceeding a dozen in either jaw—are limited to the front part of the beak, and do not extend anywhere near the nasal vacuity. This is not the case with all.

In the species named P. Kochi, which I have regarded as the type of a distinct genus, there are large teeth in the front of the jaw corresponding to those of Pterodactylus, and behind these a smaller series of teeth extending back under the nostril, which approaches close to the orbit of the eye, without any indication of a separate antorbital vacuity. On those characters the genus Diopecephalus was defined. It is closely allied to Pterodactylus; both agree in having the ilium prolonged forward more than twice as far as it is carried backward, the anterior process covering about half a dozen vertebræ, as in Pterodactylus longirostris. A great many different types have been referred to Pterodactylus Kochi, and it is probable that they may eventually be distinguished from each other. The species in which the upper borders of the orbits approximate could be separated from those in which the frontal interspace is wider.

Some of the largest specimens preserved at Stuttgart and Tübingen have been named Pterodactylus suevicus and P. Fraasii. They do not approach the species P. grandis in size, so far as can be judged from the fragmentary remains figured by Von Meyer; for what appears to be the third phalange of the wing finger is 7½ inches long, while in these species it is less than half that length, indicating an enormous development of wing, relatively to the length of the hind limb, which would probably refer the species to another genus. Pterodactylus suevicus differs from the typical Pterodactyles in having a rounded, flattened under surface to the lower jaw, instead of the common condition of a sharp keel in the region of the symphysis. The beak also seems flattened and swan-like, and the teeth are limited to the front of the jaw. There appear to be some indications of small nostrils, which look upward like the nostrils of Rhamphorhynchus, but this may be a deceptive appearance, and the nostrils are large lateral vacuities, which are in the position of antorbital vacuities, so that there would appear to be only two vacuities in the side of the head in these animals. The distinctive character of the skeleton in this genus is found in the extraordinary length of the metacarpus and in the complete ossification of the smaller metacarpal bones throughout their length. The metacarpal bones are much longer than the bones of the fore-arm, and about twice the length of the humerus. The first wing phalange is much longer than the others, which successively and rapidly diminish in length, so that the third is half the length of the first. There are differences in the pelvis; for the anterior process of the ilium is very short, in comparison with its length in the genus Pterodactylus. And the long stalk of the prepubic bone with its great hammer-headed expansion transversely in front gives those bones a character unlike other genera, so that Cycnorhamphus ranks as a good genus, easily distinguished from Cuvier's type, in which the four bones of the wing are more equal in length, and the last is more than half the length of the first; while the metacarpus in that genus is only a little longer than the humerus, and much shorter than the ulna. The Pterodactylus suevicus has the neck vertebræ flat on the under side, and relatively short as compared with the more slender and narrower vertebræ of P. Fraasii.