CLASSIFICATION.

[X]Mr Carruthers has shown me crushed Turtle-like eggs from the Stonesfield slate, which in the external pitting of the egg-shell are not so different from some birds as to preclude a suspicion that they might possibly be Ornithosaurian.

The following notes indicate structures in perfect specimens from the Lithographic slate which supplement the fragmentary remains from the Cambridge Greensand[Y].

[Y]The German animals form different family groups. And it cannot be inferred that the structures seen in them pertained to Cambridge specimens.

In the head, Cambridge specimens show no trace of the parts which are between the brain-cavity and the fore-part of the jaw. The form and condition of the orbits, nares, and of the space between them, vary in German specimens. Some Birds and certain Ruminants, such as deer, the giraffe, &c., have an interspace between the orbits and nares corresponding to that in some Pterodactyles, but no such perforation is found in living reptiles.In mammals it appears to be surrounded by the frontal, nasal, lachrymal, and often by the maxillary bone. In birds the bones appear to be the lachrymal, nasal, maxillary and premaxillary, as is the case with Pterodactyles, except that the nasal bones would seem sometimes to be excluded. The chief peculiarity of the Pterodactyle skull in this region is made by the malar bone (and, according to some authors, the maxillary also) sending up a process to meet the lachrymal. This is not seen in birds, but is characteristic of many mammals and reptiles.

The premaxillary bone is single, as in birds and Iguana; but it appears to attain as great a development as in birds, and to occupy the portion of the jaw which among reptiles and mammals is made by the maxillary bone. Owing to the great development of the premaxillary bones, the exterior nares are placed far back toward the middle of the skull as in birds, and not near the tip of the snout as in living reptiles and most mammals.

The orbits in Pterodactyles are surrounded with bone, as is commonly the case with mammals and reptiles. Among birds a complete orbit is seen among the parrots, in which it is completed below by a prolongation of the outer posterior corner of the frontal, which would correspond to the post-frontal bone, and by the lachrymal bone. Thus the malar bone, which in most mammals and reptiles forms an important part of the lower margin of the orbit, is in birds entirely excluded. In Pterodactyles the malar bone is placed between the lachrymal and the post-frontal process of the frontal bone.

The quadrate bone in German Pterodactyles, instead of being vertical as in birds, stretches obliquely forward below the malar bone, so that the articulation for the lower jaw is brought forward to be under the middle of the orbit. InPterodactylus Kochiand in other species there appears to be a process, or small separate triradiate bone, comparable to a diminished lacertian post-frontal, and homologous with the post-frontal process of the parrots. Its upper branch meets the frontal. In some genera the front appears to meet the malar. The lower branch goes to the front of the quadrate bone, and the backward branch goes to the squamosal immediately above the articulation for the quadrate bone. Thus it is a post-frontal bone resembling that of the Iguana, but modified and adapted to a cranium like that of a bird. Its form andsize in the different genera are very variable. No similar development is seen among mammals, where the post-frontals have probably ceased to exist. It is a carious point of resemblance, but from the other resemblances to Iguana being so few it is robbed of much of its force as a mark of affinity, and becomes of interest chiefly as an evidence of independent persistence of structures.

The pterygoid and palatine bones approximate to those of bird and lizard in Pterodactylus crassirostris. And the bones in Pterodactylus suevicus, which Quenstedt names vomera, should rather have been named palatines. There is a bone in Goldfuss' specimen, between the malar and palatine, which he identifies with the transverse bone, but it is not seen in any other specimen.

The ribs sometimes appear to articulate by single heads, but in P. crassirostris they are apparently articulated as in the Crocodile. Some species show abdominal ribs like those of some reptiles; but the segments of the mammalian sternum and abdominal ribs are to be regarded as homologous structures. The vertebræ offer considerable variety in size and shape, but the greatest variation in number is seen in the tail, which is sometimes stiff and long, and sometimes short. The pelvic bones show a large amount of variation in different genera, often appearing to be crocodilian, sometimes lacertian, sometimes mammalian. In the aim the humerus is variable in the length of the radial crest, and the metacarpus also varies in length.

When the external similarity of the skeletons of birds is borne in mind, it is impossible, without disregard of classification altogether, to place animals differing so widely as do the different Ornithosaurians in the few genera in which they are at present packed.

The orders of Ornithosaurians may be established hereafter. Under the name Pterosauria, Prof. Owen founded one order which has for its type the Pterodactylus longirostris.

Von Meyer proposed to separate this order into two groups, one with two phalanges in the wing-finger, of which Ornithopterus is the only example, forming hisDiathri; while the other group,Tetrathri, or those "with four fingers, comprised all other Pterosaurians. The Tetrathri he again subdivided, following out, as he states, the suggestion of Munster and Goldfuss, intoDentirostresor such Pterodactyles as have the jaws furnished with teeth to their anterior termination; and theSubulirostres, or such as want teeth at the extremities of the jaws. To the former group he left the name Pterodactylus, and to the latter was given the name Rhamphorhynchus. Von Meyer says that he might easily have made a few more species, as will be evident to those who inspect his plates, but he "believes that the students of living animals go too far in their tendency to subdivide:" a fancy that, if indulged in by Palæontologists, would have the effect of restoring the old Linnæan groups; and a complaint which, although often heard, has usually come from those who do not readily discern and appraise classificational characters. In Palæontology genera are sometimes co-extensive with orders, while species often mean genera. It may be wearisome to the collector to be lured on to follow the devious ways of a science, but Palæontology, the source whence the mysteries of existing nature must unravel their meaning, is the handmaid of all nature's truths which have been buried in evolving the existing creation; and a duty devolves upon Palæontologists to make the past an inseparable part of the present, by applying to the two the same scientific method.

A year previous to the formation of Owen's Pterosauria, Bonaparte named the Order Ornithosaurii, and divided it into a family—Pterodactylæ, and a sub-family Pterodactylinæ.

Fitzinger (Systema Reptilium, 1843) also used the same ordinal name, and recognized three genera—

Pachyrhamphus, of which the type is Pterodactylus crassirostris (Gold.).

Pterodactylus, with the type P. longirostris (Cuv.).

AndOrnithocephalus, with the type O. brevirostris (Sömm.).

These and other attempts at classification all endeavour to subdivide Ornithosaurians by the head or by the tail. Other characters for primary divisions may be obtained from the pelvis.

In the majority of German Pterodactyles the ilium extends for a long distance in front of the os pubis, and only for a very short distance behind the large ischium; and the small pubis from its anterior margin gives attachment to a large prepubic bone, whichresembles in form the os pubis of the Crocodile[Z], and is unlike that of the Monotreme. These appear to include the long-legged animals with short tails, at present called Pterodactyles, and form a well-marked family or order.

[Z]Prof. Haughton, from a study of the bones and muscles, came to the conclusion that the pubic bones of Crocodiles are the marsupial bones.

Another kind of pelvis is that in which the ilium extends a short way in front of the acetabulum, in which the pelvic bones inclose a much larger space. These include the Cambridge Ornithosaurians, the Rhamphorhynchus, and the Dimorphodon, and form another well-marked family.

These long-tailed Pterodactyles subdivide into three sub-families—Rhamphorhynchæ, Dimorphodontæ, and Ornithocheiræ. The four families may then be defined thus:

Pterodactylæ. Tail short. Hind-legs long. Ilium narrow, extending far anterior to the acetabulum; ischium extending behind the acetabulum. Epipubic bones ficiform. Head with the middle holes large, often confluent with the exterior nares. Jaws toothed to the anterior extremity.Rhamphorhynchæ. Tail long and stiff. Hind-legs short. Pubis and ischium small, oblique to ilium, which extends less far anteriorly than in Pterodactylæ. Epipubic bones narrow and bent; they unite mesially and form a three-sided bow in front of the pelvis. Head with the middle holes and nares both small. Jaws never toothed to the anterior extremity.Dimorphodontæ. Tail long and stiff. Hind-legs long. Pubis and ischium forming an expanded sheet of bone at right angles with the narrow ilium, which extends as far behind as in front [prepubic bones triangular (?) attached by the apex of the triangle]. Head with the nares and middle holes large. Quadrate bone large. Jaws with large teeth at the extremities, and small teeth behind. No sacrum.Ornithocheiræ. Tail long and flexible. Hind-legs short. Pelvis as in Dimorphodontæ. [Epipubic bones with a small attachment, form unknown.] Head with the quadrate bone small. Sacrum of not fewer than three vertebræ.

Rhamphorhynchæ. Tail long and stiff. Hind-legs short. Pubis and ischium small, oblique to ilium, which extends less far anteriorly than in Pterodactylæ. Epipubic bones narrow and bent; they unite mesially and form a three-sided bow in front of the pelvis. Head with the middle holes and nares both small. Jaws never toothed to the anterior extremity.

Dimorphodontæ. Tail long and stiff. Hind-legs long. Pubis and ischium forming an expanded sheet of bone at right angles with the narrow ilium, which extends as far behind as in front [prepubic bones triangular (?) attached by the apex of the triangle]. Head with the nares and middle holes large. Quadrate bone large. Jaws with large teeth at the extremities, and small teeth behind. No sacrum.

Ornithocheiræ. Tail long and flexible. Hind-legs short. Pelvis as in Dimorphodontæ. [Epipubic bones with a small attachment, form unknown.] Head with the quadrate bone small. Sacrum of not fewer than three vertebræ.

In the Pterodactylæ the genera are—

Pterodactylus(Cuvier), in which the exterior nares are at the sides of the face, very large, and only partially, if at all, separated by bone from the small middle hole of the head. The head is elongated. The neck is long. Among others, it includes the species P. longirostris, P. Kochi, P. scolopaciceps, P. longicollum.Ornithocephalus(Sömmerring), in which the anterior nares are entirely separated from the middle holes of the head, both being small, and the latter exceedingly small. The head is short The neck is short. The large ischium appears to be excluded from the acetabulum, and the ilium appears to extend less far forward than in Pterodactylus[AA].

Ornithocephalus(Sömmerring), in which the anterior nares are entirely separated from the middle holes of the head, both being small, and the latter exceedingly small. The head is short The neck is short. The large ischium appears to be excluded from the acetabulum, and the ilium appears to extend less far forward than in Pterodactylus[AA].

[AA]So far as can be judged from figures, it appears to have but three bones in the wing-finger: what Cuvier regarded as a terminal and fourth joint, the bonen, Pl.XXIII.fig. 7,Oss. Foss., appearing to me to be the fibula of the tibia markede.sin the same figure would be the terminal phalange, andrthe first phalange, as may be proved by measuring them with those of the other hand, so that a phalange is missing from between them. Both the terminal phalanges appear to be hooked at the termination. Goldfuss figures the phalanges so as to make the bone which appears to be fibula in Sömmerring and Cuvier look like a fourth phalange.

Pachyrhamphus(Fitzinger). The nares are entirely separated from the middle holes of the head; both are large. The head is thick and massive. The prepubic bones meet mesially. No evidence of the number of phalanges in the wing-finger. The quadrate bone is massive, but has small attachment to the skull. Two sacral vertebræ. Wing-metacarpal very short. The type is P. crassirostris (Goldfuss).Cycnorhamphus(Seeley). Nares very small, looking upward from a swan-like beak. The middle hole of the skull very large and elongated and lateral. Neck long. Wing-metacarpal long. Four joints in the wing-finger. Ilium widening in front. Epipubic bones meeting mesially. The type is Pterodactylus suevicus (Quenstedt).

Cycnorhamphus(Seeley). Nares very small, looking upward from a swan-like beak. The middle hole of the skull very large and elongated and lateral. Neck long. Wing-metacarpal long. Four joints in the wing-finger. Ilium widening in front. Epipubic bones meeting mesially. The type is Pterodactylus suevicus (Quenstedt).

In the Rhamphorhynchæ at present there appears to be but one genus known:

Rhamphorhynchus (von Meyer). The nares and middle holes are both small, ovate, of nearly equal size, and close together at the side of the head in front of the orbit.

In the Dimorphodontæ the only genus is

Dimorphodon(Owen). It has the nares enormously large. The middle holes are also large.

In the Ornithocheiræ the genus is

Ornithocheirus(Seeley), in which teeth are prolonged anterior to the muzzle, and the palate has a longitudinal ridge.

With the osteological illustrations of the Ornithosauria are arranged some premaxillary bones, which show varieties of form of the snout. These variations of shape serve easily to indicate different species. And the following memoranda from those specimens and other specimens in the drawers form a synopsis of the species of the Cambridge genera, which may hereafter be fully elucidated from the copious materials in the series of associated remains.

Case.Comp.Tablet.Specimen.Jc132

Ornithocheirus Sedgwicki(Owen).

The fragment is 27/8ths inches long, with the elliptical teeth opposite to each other, 6 on a side on the palate, and one pair in front. The first three teeth are large; behind these the teeth are about half the size. The palate is gently convex, with a faint median ridge, and measures from side to side over the fourth and subsequent sockets13/16ths of an inch. The height of the jaw at the fourth socket 11/4inch. The sides converge to an acute rounded rostral keel. The jaws appear to have been long. The anterior termination is vascular.

The rostral keel figured by Owen Pl.I, fig. 1d, in the 1st Supt.Cret. Reptiles, is not square as represented there, but rounded; the sides converge more acutely, and at the ridge the keel is not half so wide as the figure makes it. The enormous size of the third tooth-socket is partly due to the cracked bone having absorbed more phosphate of lime than it could hold, and extended the cracks to fissures. The type specimen shows that there was another pair of sockets in front of, but quite close to, those which appear to terminate the lower jaw.

II.

Case.Comp.Tablet.Specimen.Jc151—3

Ornithocheirus Cuvieri(Bowerbank).

A portion of a premaxillary bone fractured at both ends, and two inches long, corresponds with Dr Bowerbank's fossil figured Pl.XXVII.fig. 1, 3, 4, in the Palæontographical volume for 1851. The palate is just as wide; the median ridge, the same; the teeth the same in shape and as far apart. The jaw is of the same depth, but does not deepen so rapidly behind. The only other difference is that the sockets of the teeth are less prominent on the sides, and appear to look more directly down.

The ridge in which the converging sides meet is well rounded in a dentary bone which may have pertained to this species. In the space of two inches and a quarter are 5 teeth, the posterior four extending over two inches, the other pair being in front. The palatal surface is3/4of an inch broad behind the third tooth, and rather more than5/8of an inch broad behind the fourth tooth. The length of the 4th or of the 5th sockets is two-thirds that of the second or third. In front of the 5th tooth, the jaw is an inch deep, and it tapers in a curve to the anterior end. The teeth behind the third have interspaces greater than the length of the sockets; that between the 4th and 5th being3/8of an inch, while the socket only measures a quarter of an inch long. Behind the 2nd socket commences the palatal groove, broad in fronts but narrowing behind; and its sides instead of diverging as in the type, are concave so as to form a channel like a straightenedSiliquariashell. The halves of the palate bevel off so as to make a right angle with each other, and greater angles with the flat sides.

III.

Case.Comp.Tablet.Specimen.Jc6351

Ornithocheirus machærorhynchus(Seeley).

Dentary bone. Broken at both ends, and wanting all its teeth, this interesting fossil shows the suture where its whole length rests on the angular bone which almost reached to the termination of the beak, quite unlike what is seen in any German Pterodactyle.

It is a narrow mandible, less than three quarters of an inch wide, with the alveolar margins parallel. The palatal surface 11/2inch long, is divided into 3 equal strips; the middle one being a deep glossal groove, slightly narrowing in front, and deepening behind, made by two inclined flat surfaces. The lateral strips are horizontal behind, and in front slope a little outward. The tooth-sockets are oval, directed outward, and as long as the interspaces, though these seem to get longer behind. In an inch and a quarter there are four teeth. Below the teeth, the sides of the jaw are compressed: though nearly parallel at the hinder fracture, the flattened surfaces approximate in front till they meet in a sharp keel, which appears to make an acute angle of about 45° with the palate; and below, where the jaw is an inch deep extends for half an inch in front of the suture with the angular bone: this suture is straight and irregularly concave, and in an inch and a quarter approximates to within5/8ths of an inch of the palate.

IV.

Case.Comp.Tablet.Specimen.Jc2121

Ornithocheirus tenuirostris(Seeley).

Middle part of a premaxillary bone fractured behind and in front, slightly distorted by compression; it is 21/8th inches long, and nearly resemblesO. compressirostris(Owen). The palate is about1/2an inch wide in front, and5/8ths of an inch wide behind; it is compressed mesially into a strong angular keel, between which and the teeth there is a shallow groove on each side. The groove dies away behind, and the converging parts of the keel occupy the whole space between the teeth. The teeth-sockets are small, elliptical, not opposite to each other, and placed along a distinct flattened tooth area, which looks downward and outward and separates the palate from the side of the jaw. The first pair of sockets preserved are almost3/16ths of an inch long and1/16th of an inch wide. The interspace between that tooth and the next tooth behind is7/16of an inch. Separated by similar interspaces, behind these on one side are two sockets, and on the other side one socket. The sides are flattened in front, and convex behind, (making the section of the jaw lanceolate); they are compressed and round into a narrow rostral keel. The height from thepalatal ridge to the rostral keel in front is11/16ths of an inch; behind it is fractured, but the height was probably14/16ths of an inch.

The palatal keel, distance of the teeth, and proportions of the jaw, distinguish it from O. compressirostris (Owen).

Case.Comp.Tablet.Jc20

Ornithocheirus Oweni(Seeley).

The small piece of premaxillary on which this species is founded indicates a small animal, and nearly resembles the jaw ofO. microdon.

It is scarcely an inch long; nearly9/16ths inch high behind, and nearly7/16ths of an inch high in front, so that it tapers very rapidly, and could scarcely have been an inch longer in front.

The nose is well rounded, but the sides are a little concave, and become well pinched in in the middle, behind, showing the near approach as I think to the nostril.

The palate half an inch broad, is divided into two concave channels by the strong and sharp median ridge, which projects below the alveolar margins. The dental margins are not rounded as inC. microdon, but flattened, making more than a right angle with both the outer side-wall and palate. The interspaces between the teeth are rough, looking as though they had supported minute teeth. The alveolar margin is a tenth of an inch wide; along it are the perfectly circular sockets, a sixteenth of an inch in diameter. There are 3 sockets between5/8of an inch, so that they are separated by 3 times their diameter. The palate is obliquely impressed with blood-vessels running forward to the teeth from the median ridge.

The points in which this jaw differs from that ofO. microdonare that in this species the teeth are circular instead of being oval; that the interspaces here are as long as in that species, though this jaw is only two-thirds the width; that instead of having a sharp keel on the upper surface, this has a well rounded roof. That though the jaw is scarcely higher than it is wide, it shows strong furrows running up to the nares, while inO. microdon, though the proportions are thesame, the sides are perfectly flat without trace of pinching in, while the line of the nasal opening is indicated by a faint furrow running all along the jaw. And lastly it differs in size, which, where the sutures are lost, may be important in discriminating forms.

VI.

Case.Comp.Tablet.Specimen.Jc291—2

Ornithocheirus microdon(Seeley).

Premaxillary bone. The fossil is nearly 13/4ths inch long, and at the proximal end, where it is less than3/4ths of an inch high, has flat sides, which converge to form a keel which is depressed anteriorly and rounded so that where fractured in front the bone is7/16ths of an inch deep. The palatal surface contains two wide concave channels, between which descends a sharp median ridge, which behind becomes more prominent than the alveolar border.

The palate is5/8ths of an inch wide. The alveolar margins are compressed and rounded. The small tooth-sockets are oval, and four are contained in 11/8th inch; they look downward.

There is a small tip of a jaw associated with this fossil, which is so like that it might be part of the bone broken off before fossilization. It corresponds in every way except that the teeth are closer. In this terminal lanceolate fragment there are in5/8ths of an inch four teeth. The snout is terminated by two, which are close together.

VII.

Ornithocheirus Huxleyi(Seeley).

The only specimen of this species yet known is the greater part of a dentary bone contained in the Museum of the Geological Survey. An inch and1/4long and3/4ths of an inch wide, it is less than half an inch deep: the sides slowly converge towards the front, and it appears to have had an obtusely lanceolate beak. The under surface is convex, too inflated for trace of a keel, and tapers to the end of the beak, which, with the left alveolar margin is abraded. The palatal surface is smooth at its front end, but two diverging ridges soon arise and form the boundary of a posteriorly deepening mesial channel, which is a quarter of an inchwide at the fracture. These ridges too, which are parallel with the compressed and rounded alveolar margins, convert the lateral spaces into shallow channels. The right side shows the sockets of 3 small oval teeth separated by interspaces wider than teeth. A tooth and two interspaces measure7/16ths of an inch.

The only cretaceous Pterodactyle which this at all resembles isO. microdon, but the palate is wider than in that species; the sides converge towards each other more rapidly, as though it belonged to a species with a shorter snout.

I am indebted to Prof. Huxley for the opportunity of making a notice of this species.

VIII.

Case.Comp.Series.Specimen.Jc2131

Ornithocheirus oxyrhinus(Seeley).

This well-marked species is a portion of a premaxillary bone 11/4inch long, fractured behind and in front. The palate is half an inch wide; its two halves are inclined to each other at a considerable angle, and where they meet form a more prominent keel. The tooth-sockets look more outward than downward, are nearly circular, separated by interspaces as long as the sockets; three sockets and two interspaces measure one inch. The jaw is about5/8ths of an inch high in front, and about1/16th of an inch higher behind. The sides are flat and converge like the sides of a wedge to a sharp rostral keel.

IX.

Ornithocheirus xyphorhynchus(Seeley).

I have seen but one example of this form. It has lost much of the outer layer of bone, and shows on the sides impressions like tooth-marks from an eater of Pterodactyles. A groove which has some appearance of being due to fracture traverses each side, but the specimen is symmetrical, and has its characters in no way changed by the accident.

It is a portion of a lower jaw of a long-beaked Pterodactyle of theO. Sedgwickitype, with parallel sides, and the rounded basal ridge nearly parallel with the palate.

The fragment is two inches long, showing four large andobliquely set sockets in If inch. The tooth-sockets are on the outer two-thirds of the palate, and looked forward, upward, and outward The interspaces each measure5/16ths of an inch.

Each half of the palatal surface which is5/16of an inch wide, inclines to the other half at a right angle, being parted by a narrow groove; the diameter of the jaw is half an inch.

The depth of the jaw is5/8ths of an inch in front, and3/4ths of an inch behind. The sides are flat and approximate below to a sharp keel. This species is one of many in the collection of W. Reed, Esq. of York, kindly placed in my hands for the elucidation of those in the Woodwardian Museum.

Case.Comp.Tablet.Specimen.Jc141, 2

Ornithocheirus Fittoni(Owen).

The fragment is 11/2inch long, with two large elliptical tooth-sockets on each side of the flattened palate, and one pair in front. The third socket is separated from the fourth by a considerable interspace. Between the third sockets arises the median palatal ridge, and from the inner margin of each socket a lateral ridge appears to be continued. Behind the third socket the jaw measures11/16ths of an inch from side to side, and10/16ths of an inch high. The sides converge and round convexly into each other. The jaws appear to have been long; It is only known by upper jaws. The type specimen shows the socket of another tooth in front of the last one figured by Prof. Owen. It is directed outward at a greater angle, and separated from the hinder one by a wall not1/16th of an inch thick, and the teeth of this pair must have been parted from each other by a film equally thin. There is no truncation of the snout as inO. Woodwardi.

Another specimen shows some variations. This fragment of a premaxillary bone is fractured through the third pair of tooth-sockets in front and through the seventh pair behind. It is about 21/8th inches long; the palate is11/16ths of an inch wide behind the great tooth, and maintains the same width. The jaw is11/16ths of an inch high behind, and10/16ths high in front. The sides are gently convex, and imperceptibly unite to form the well-rounded depressed mesial ridge of the beak. From the front of the thirdto the back of the fifth socket measures 13/8ths inch. The sockets are ovate, rather smaller, and closer together than in the type ofO. Fittoni; margins elevated. The variations from types are so many, and often so considerable, as to suggest the idea that the fossil groups called species may in the living animals have often been genera.

In all the specimens the end of the palate is a little reflected upward.

XI.

Case.Comp.Series.Specimen.Jc191

Ornithocheirus dentatus(Seeley).

A fragment of premaxillary bone two inches long, fractured behind the socket for the seventh tooth. It most nearly resemblesO. SedgwickiandO. Cuvieri. Behind the second tooth the palate is1/2an inch wide; behind the sixth socket it is5/8ths of an inch wide; the distance between these points is nearly 11/2inch. The palate is flattened, with a sharp slight mesial keel and a wide concave channel on each side which dies away in front. The first pair of teeth are in front of the snout, rather small, and look forward. In this specimen the large third tooth is not developed on the left side. The second and third sockets are large and close together; the succeeding teeth are parted from each other by interspaces equal to their own diameter. They are gibbously elliptical. The sides of the jaw are gently convex from above downward; they round into each other to form a narrow rostral keel. Behind the second socket the jaw is1/2an inch high; behind the sixth it is nearly7/8ths of an inch high.

The grooved and relatively wider palate, and the relatively smaller teeth, abundantly distinguish this species fromO. Sedgwicki(Owen).

The smaller, more circular teeth, placed closer together, distinguish it fromO. Cuvieri(Bowerbank).

XII.

Case.Comp.Tablet.Jc22

Ornithocheirus scaphorynchus(Seeley).

This fragment of premaxillary bone is 11/2inch long. The palate is1/2an inch wide behind, and the jaw is rather more than1/2an inch high; behind the second tooth it is nearly5/8ths of aninch high. The sides converge superiorly to form a well-rounded keel. The palate is flattened, with a slightly elevated blunt median keel. There appears to be a pair of small teeth in front of the snout as usual, and six on the palate, with an indication of another at the posterior fracture. The teeth are of moderate size and almost circular. In the form of the bone it is readily distinguished from all the species enumerated.

XIII.

Case.Comp.Series.Specimen.Jc6321

Ornithocheirus platystomus(Seeley).

An ill-preserved fragment fractured in front and behind, yet indicating a distinct species. The palate is flat, with the faintest median ridge, and the sides are flat and round into a narrow rostral keel, which in front approximates rapidly towards the palate. The first pair of sockets are missing; what appears to be the second pair are about1/8th of an inch long, separated from the pair behind by an interspace of1/4th of an inch. These are ovate and less than1/4th of an inch long, and separated from the next pair by an interspace of not less than1/4th of an inch. The height of the jaw over the first pair of sockets preserved is9/16ths of an inch; over the second pair it is14/16ths of an inch; the space between these points is9/16ths of an inch. Behind the second pair of teeth the palate is nearly5/8ths of an inch wide.

The only species which it resembles isO. brachyrhinus, but differs from that in the flatter, narrower palate, which makes a greater angle with the rostral keel, and in the smaller teeth, which are separated by wider interspaces.

XIV.

Case.Comp.Series.Specimen.Jc2111

Ornithocheirus nasutus(Seeley).

A fragment of a premaxillary bone 6 inches long. It somewhat resemblesO. Cuvieriin the aspect of the palate, but the jaw is more elongated, and expands from side to side at the anterior end. The teeth are opposite to each other in front, but become irregular after the sixth. The palate measures behind the second pair of sockets3/4ths of an inch, behind the third pair it is a sixteenth of an inch wider, behind the ninth pair half an inch, and in thelast two inches it begins to widen again. A sharp keel arises behind the second pair of sockets and becomes more prominent to behind the tenth pair, when the channel which accompanies it on each side seems to disappear. The first pair of teeth, which look forward, is smaller than the second and third pairs; they are closer together than those which follow. The third sockets are7/8ths of an inch from the tip of the snout. Then follow three smaller, more circular teeth, which are separated from each other by interspaces as long as the sockets. The back of the sixth sockets are 21/4inches from the tip of the snout. Then follow two larger more elliptical sockets; after which the sockets become smaller and are separated by longer distances, that between the 10th and 11th pairs is nearly3/4ths of an inch.

The height of the jaw behind the second pair of sockets is5/8ths of an inch, behind the sixth sockets15/16ths, behind the tenth sockets 11/4inch. In front, the nose has the aspect of being compressed from above downward, and behind it is compressed from side to side. The sides are flattened and round into a narrow rostral ridge which is depressed at the anterior end.

XV.

Case.Comp.Tablet.Jc21

Ornithocheirus polyodon(Seeley),

This species is founded on the anterior end of a premaxillary bone; in form not unlikeO. Fittoni. It is5/8ths of an inch wide; the lateral margins approximate very slowly, and in front it appears to be truncated. It is an inch and a quarter long, and in that space were on each side six large round teeth, almost as close together as they could be, five on the palate and a pair in front. The terminal two are no wider apart than the rest, and point more forward. A moderate, sharp, median ridge descends in the flattened palate, making its lateral halves a little concave. The front termination of the palate is slightly reflected upward. The jaw, which is1/2an inch deep behind, tapers to its termination more rapidly than doesO. Fittoni. The flat sides similarly converge, and form a well-rounded ridge, which does not get blunter in front. From their close approximation, it results that the tooth-sockets are entirely above the palatal surface, so that they are better seen from the side of the jaw than from the palate.

It is a clearly marked species, as well distinguished fromO. Fittoniby the closeness of its teeth, asO. Sedgwickiis fromO. Cuvieri.

XVI.

Case.Comp.Series.Tablet.Jc5281

Ornithocheirus denticulatus(Seeley).

This is a species which can only be confounded with O. polyodon. It is a fragment of premaxillary bone 13/4inch long, fractured through the seventh socket. It differs from O. polyodon in having larger teeth, which are wider apart, look more downward, have a narrower palatal interspace between each pair, and a rostral keel, which is more compressed from side to side behind and from above downward in front, and makes a greater angle with the palate.

The sockets are more uniform in size and closer together than usual, the second and third pairs being but slightly larger than the others; all are broadly elliptical. The palatal keel becomes sharp and prominent behind the fourth sockets. Behind the second pair of sockets the height of the jaw is nearly7/16ths of an inch, behind the fourth sockets the height is10/16ths of an inch; the distance between these points is about10/16ths of an inch.

XVII.

Case.Comp.Series.Tablet.Jc122

Ornithocheirus crassidens(Seeley).

This is a fragment of a ?premaxillary bone, fractured behind through the socket for the fourth tooth. It approximates to O. colorhinus, but differs chiefly in the nose not extending in front of the first pair of teeth; in there not being any lunate area above the first pair of teeth; in there being but one tooth in front, which is relatively large; in the socket for the fourth tooth being quite close to that for the third tooth, and in the palatal sockets looking much more outward. The nose also appears to be better rounded.

The fragment is 17/8inch long. The second and third sockets, with their interspace, measure 11/8inch. On the opposite side the first socket is intermediate in position between the first and second.

Though not likely, it is just possible that this might be the premaxillary bone of O. eurygnathus.

XVIII.

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