Prof.H.G.Seeky—On the Ornithocheirus. 13 In Glaseia the spirals are connected as in Atryp'a, but it materially differs from this genus in the direction of its spirals. For more ample details readers are referred to my forthcoming Monograph. (To be continued.)

II.—ON EVIDENCE OP TWO ORNITHOSATJRIANS REFERABLE TO THE GENUS OBNITHOCHH/KUS, FROM THE UPPER GREENSAND OF CAM- BRIDGE, PRESERVED IN THE COLLECTION OF W. EEED, Esq., F.G.S. By Professor H. G. SEELEY, F.R.S., F.G.S., etc. (PLATE I.) rPHE fragments of jaws of Ornithosaurs from the Cambridge J. Greensand show a greater variety in size, form, and proportion than those from any other formation. The largest species were apparently the most singular in the shape of the snout, but after five-and-twenty years of collecting we still seem destined to know them only from fragments which, though extraordinary and sugges- tive, are tantalizing from their imperfect condition. It is impossible to tell whether the head was short or long, or what proportion it bore to the body, in the oase of these isolated specimens, but some of them, like the jaw-fragment which I am about to describe, show a power of tooth and massiveness of bone which could only have pertained to one of the most destructive and probably one of the largest of these . This specimen, the anterior extremity of a jaw, was submitted to me fourteen or fifteen years ago, by the courtesy of W. Eeed, Esq., "F.G.S., of York, and I then made the note on Ornithocheirus lieedii as well as the description of Ornithoclieirus xyphorhynchus, a jaw of a slender and altogether different type, which were included in 1870 in my book on the Ornithosauria. The specimens have again been entrusted to me, for fuller description, but they still remain unique examples of the species of which they are types. Unfortunately, only the smallest portion of the palate is preserved in Ornitho- cheirus lieedii, as though the specimen had lain snout downward in the mud, and all the bone posterior to it had decayed. This fragment of the palate is not more than a millimetre and a half long in the median line where it is shortest, but it shows distinctly a deep narrow median groove, hardly more than a millimetre wide, which expands anteriorly and divides into two branches in a V shape. This condition of a median groove in the jaw-bone has hitherto been considered, and I believe correctly, to be distinc- tive of the lower jaw, and I therefore propose, notwithstanding the arrangement of teeth, which led me originally to regard it as a pre-maxillary bone, now to interpret it as the anterior portion of a dentary bone. I am led to this view also by the external form, which indicates a rapid compression of the sides towards the lower part of the jaw, and also by a remarkable oblique truncation of the under side of the mandible, which is somewhat paralleled in the Ornithoclieirus maclieerorhynchus (Ornithosauria, pi. xii. fig. 1). The

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http://journals.cambridge.orgDownloaded: 11 May 2016 IP address: 130.130.37.84 14 Prof. H. G. Seeley—On the Genus Ornithocheirus. palate, though badly preserved, was convex on each side of the median groove, and between the first pair of palatal teeth the width was twenty-two millimetres. The palatal ridges become depressed a little as they approach its anterior termination, and there appear to be a pair of small pits in front of them, external to the V-shaped termination of the palatal groove. The teeth which formed the anterior corners of the jaw [Fig. 36 (5)] are only indicated by the bases of the crowns, which were circular. Each is fifteen milli- metres in diameter, or about equal to a medium-sized tooth of an Ichthyosaurus, and perhaps as large as any Plesiosaurian tooth. Each tooth is contained in a socket, which approaches within about a millimetre of a lateral wall of the jaw, and within about two or three millimetres of its anterior termination. The bone behind the tooth-socket rounds convexly from the lateral palatal inflation into the external side of the jaw, without any limiting ridge or angle. This pair of teeth was directed somewhat forward as well as upward and outward, and it may be presumed that the outward angle was determined by the inferior convergence of the lateral walls of the jaw. Behind this pair of teeth, and separated from them by an interspace of five or six millimetres, was another pair, of which only an indication of the anterior wall of the sockets remain. These show that the second pair of teeth were separated by a wider breadth of the palate. The sockets are not directed upward at quite the same angle, and that on the right side shows the fang to have been imbedded in the jaw for a depth of about thirty-five millimetres. The bony surface at its posterior fracture is black, rough, and corroded, as though by exposure on the sea- bed, and displa37s one or two fragments of incrusting shells. The anterior face of the specimen is triangular, formed about a right- angle apparently with the palate, and contains in its upper part the broken stumps of two pre-palatal teeth. This anterior region is about thirty-five millimetres deep, and at its widest part at the outer corners of the palatal tooth-stumps is fully thirty- five millimetres wide. The sides, which converge inferiorly, are about thirty millimetres long, and round into each other in an ill-defined way ; the upper part especially of the lateral wall of the jaw rounds convexly towards the tooth-stumps in its upper part already alluded to, but it is margined by a slight ridge. The superior outline is three-sided, and consists of a middle horizontal portion, with lateral parts sloping outward and downward in front of the palatal teeth. The tooth-stumps on this anterior face [Fig- 3a (p)] are three or four millimetres below the anterior border of the palate, and are separated from each other by an interspace of less than half a centimetre. The bone of this interspace in its upper part is smooth and marked by a relatively wide and moderately deep groove, which dies away towards the palatal margin. The tooth sockets are ovate, probably from the direction of the section of the tooth, one and a half centimetre deep, and over a centimetre wide. They were probably circular, since they are seen to have been directed forward at a greater angle than the palatal teeth. The anterior space

http://journals.cambridge.orgDownloaded: 11 May 2016 IP address: 130.130.37.84 Prof. H. G. Seeley—On the Genus Ornithocheirus. 15 below these tooth sockets has the surface less well preserved than the upper part, but it was marked by a median inflation below the teeth, and concavities on each side, which converge to a median concavity that becomes continued on the under side of the jaw. The median oblong boss between the teeth appears to have been roughened with two longitudinal grooves, and the whole of this inferior region gives indications of rugosities, as though fleshy lips might have extended forward below the teeth, and there are no in- dications of blood-vessels perforating the bone, such as might have been anticipated if it had been sheathed in horn. The basal oblique truncation which forms a prolongation of this anterior region down- ward and backward is concave in length, a feature seen in no other Greensand Ornithosaur. It is about three and a half centimetres long, and has a shallow median groove about seven millimetres wide, which appears to become shallower as it extends backward. It is margined by convex ridges, which at first round obliquely into the sides of the jaw, but nialie a smaller angle with it as the jaw becomes more compressed from side to side in its backward exten- sion. The fragment which is preserved of the lateral surfaces of the jaw shows smooth bony tissue, is concave from above downward, and nearly flat from before backward, and, as already remarked, rounds into the adjacent bony surfaces. These lateral areas are sub-rhomboid, are preserved for an antero-posterior extent of hardly more than three centimetres, while the depth of jaw indicated by the fragment is six and a half centimetres, probably a good deal short of its depth when perfect. The extreme posterior width of the specimen behind the first pair of palatal teeth is four and a half centimetres, and the width of the jaw where fractured at the posterior termination of the base is one and a half centimetre. In 1869, in my index to the Eeptilia, etc., in the Woodwardian Museum, I gave a list for the use of students of species which might be founded upon the Pterodactyle remains therein enumerated from the Upper Greensand, and I further grouped these species into two genera, which were named though not fully characterized. Pteno- dactylus was used for twenty-one species, all more or less allied in character to the Pterodactylus Sedgwichi of Owen. The other genus, Ornithocheirus, included three species, and had for its type the Pterodactylus simus of Owen, it being mentioned in a note that the genus was distinguished by having no teeth anterior to the palate, a character which inferentially distinguished it from the other new genus. A month or two later, in the beginning of 1870, " The Ornithosauria" was published, and in that book I temporarily abandoned the division of the species into separate genera, not because they seemed to be incapable of definition, but because the species appeared to be capable of division into more than two genera, and I thought it inexpedient to characterize them until the whole of the- evidence could be fully put forward, and supported by means of figures. The name Ptenodactylus was therefore abandoned and the •whole of the species described were temporarily referred to Ornitho- cheirus. This genus was defined (p. 112) as having teeth prolonged

http://journals.cambridge.orgDownloaded: 11 May 2016 IP address: 130.130.37.84 16 Prof. H. G. Seek?/—On the Genus Ornithocheirus. anterior to the muzzle, and as having a palate with a longitudinal ridge. After giving briefly the characters of snouts or mandibles of twenty-four species in that memoir, it was remarked (p. 127), " The species which follow were separated in the Index (to the Ornitho- sauiia, etc.) as a different genus. That proposal might still be sustained, for these massive truncated jaws are unlike the spear- shaped jaws of many of the species, and to the minds of some readers the forms already described will arrange themselves in groups which not improbably indicate genera; but a re-examination of the type Pterodaclylus simus, Owen, has convinced me that it is a lower jaw, and therefore it affords no evidence of the presence or absence of the peculiar front pre-maxillary teeth which characterize nearly all the species." Since that date circumstances have delayed my intended description of these fossils in detail; but in 1874, Prof. Owen, in a Monograph on the Pterosauria, published by the Palasontographical Society, after referring to the tapering snouts which formed Von Meyer's group of Pterodactyles named Subulirostres, observed that the series might be traced to other forms in which the snout became so shortened as to be truncated ; and such forms he suggested might be named Truncirostres. He then (p. 6) goes on to observe that the species of this family which have the foremost pair of teeth projecting forward in the upper jaw from the truncate surface at a higher level than the alveolar border form the genus . That there may be no mistake about the nature and limits of this genus, the species Coloborhynchus Sedgwichi and C. Cuvieri are quoted as examples. I am unable to detect any differ- ence between Prof. Owen's definition of that genus and my previous definition in 1870 of Ornithocheirus ; while Prof. Owen, by quoting the types which I had placed at the beginning of my enumeration of the species of Ornithocheirus, conclusively shows that he intends his name as a synonym. As it is not usual for any author knowingly to burden nomenclature with synonyms without justification, Prof. Owen added a note stating that he " has no evidence, and Mr. Seeley has given none, of such departure from the Pterosaurian type of hand as would justify the term Ornithocheirus proposed by Mr. Seeley in 1870, in his Ornithosauria (p. 112), or the term Ptenodac- tylus previously proposed by Mr. Seeley for the same Pterodactyle in the Index to the Fossils, etc., in the Woodwardian Museum." I certainly was under the impression that the genus had been sufficiently explained in the characters set forth in the descriptions of the skeleton between pages 28 and 94 and between pages 112 and 128 of the " Onithosauria." But Prof. Owen implies in this note that the Pterosaurian type of hand is a fixed quantity already known to him, and as I had already in previous writings expressed my dissent from the interpretation which Prof. Owen had given of the Ornithosaurian carpus, I may perhaps fairly claim that Prof. Owen is not altogether an un- prejudiced judge as to what the Pterosaurian type of hand really is. It seemed to me that the carpus, as I have stated in the Orni- thosauria (p. 48), consists in Ornithocheirus of "three bones

http://journals.cambridge.orgDownloaded: 11 May 2016 IP address: 130.130.37.84 Prof. H. O. Seeley—On the Genus Ornithocheirus. 17 arranged as a proximal carpal, a distal carpal, and a lateral carpal, Two of them are figured by Prof. Owen, who regarded the distal carpal as scapho-cuneiform ; while a very imperfect example of the proximal carpal is named the unciform : neither of these determi- nations, the reverse of those that follow, were given as more than probable guesses." In "Eemarks on Prof. Owen's Monograph on ," published in the " Annals of Nat. Hist," for Aug.* 1870, I gave a figure of the carpus and adjacent bones in the genus Ornithocheirus, side by side with the corresponding bones of the ostrich, such as I had been accustomed to exhibit in my lectures at Cambridge. Prof. Owen has never called in question either that nomenclature of the carpus, the restoration of it, or the reasons given for so reconstructing it; and I venture to repeat that the carpus is a portion of the hand which is, in this type, so eminently bird-like in the form and arrangement of its elements as amply to sustain the name which I gave the genus, if indeed it needed any such justification. I am therefore at a loss to understand the imputation that I have adduced no evidence which would justify the term Ornithocheirus. Since that date, in the Journal of the Linnean Society for JJecember, 1876 (pp. 98 to 103), I have discussed anew the characters of the hand in Ornithoeheirtis, showing that this genus possessed three well-developed metacarpal bones, of which two were large, like the metacarpals of birds, and I am quite content, if a name can be called in question on such grounds, to leave its defence to the evidence there set forth. The Ornithosaurs, however, all have the ornithic type of hand, and make no approximation to the structure of hand seen in either reptiles or mammals. But if we are to begin calling in question the fitness of generic names, and proceed to cancel them whenever any new interpretation is supposed to make them more or less inappropriate, nomenclature will be in a constant state of flux whenever names aspire to convey interpretations of characters. Thus we have Ceteosaurus ; there is nothing whale-like in this Saurian, it was not even an inhabitant of the water, but the name sufficiently served the purpose of indicating a type of structure which has since become better known. Similarly Bylaosaurus, if it means anything at all, signifies a wood Saurian: and it may be doubted whether evidence has been adduced which would justify such a name. I am not concerned to defend the name Ptenodactylus, because it has been abandoned in my later work; but I imagine the name might be used to indicate a " winged Saurian," without any undue stretching of meaning; and I therefore urge, that until gome weighty reasons for discarding the generic names which I gave to the Greensand Ornithosaurs are adduced, there will be no need ft* any one to remember that the genus Goloborhynchus was ever instituted. I have found it necessary to make this explanation because almost the only fossil which closely resembles the species which I have here described is a species from the Hastings Sand, which Prof. Owen has described under the name Ooloborhynchus clavirostris. From the figure it is impossible to tell whether it be a pre-maxillary or dentary bone, but from its close resemblance in

DECADE II.—VOL. VIII.—NO. I. 2

http://journals.cambridge.orgDownloaded: 11 May 2016 IP address: 130.130.37.84 18 Prof. H. Q. Seeley—On the Genus Ornithocheirus. some respects to this .species, I suspect it will prove to be dentary. It, however, differs in presenting a nearer approximation to the type of Ornithocheirus simus, and it entirely wants the somewhat flattened oblique inferior area, which in Ornithocheirns Beedii is concave from front to back. The teeth, however, are nearly circular. The species now described differs from Ornithocheirus capito (Ornithosauria, p. 126), in the circumstance that the teeth in that species are elliptical. ORNITHOCHEIRUS XYPHORHYNCHTJS (Plate I. Fig. 2a and 26). This species was founded upon a fragment from the middle of a lower jaw, which measures 5^ centimetres in length, and must have presented an unusually dagger-like form. There is a narrow median groove running along the palate. The base of this groove is sharp, and its narrow sides diverge upward and outward, and round into the palate, so that it appears to be margined by a ridge on each side, about a millimetre wide. The palate is formed of two lateral portions, which look obliquely upward and outward, and are inclined to each other at a right angle. The width of the palate at its outer limit is 13 millimetres; the depth of the inclined lateral halves of the palate is on each side about eight millimetres. The palatal surface shows on each side four tooth-sockets, better pi'eserved on the left side than the right. The sockets are placed on the outer part of the palate, at a distance of four millimetres from the median groove. The interspace between the first two sockets is eight millimetres, and between those which follow a trifle more. The sockets are ovate, and placed obliquely so that the anterior margin of the tooth inclines towards the inner part of the palate, and its hinder margin towards the outer limit of the palate, where the bone is elevated a little as usual.1 The interspaces are slightly concave from front to back, and the inner and hinder border of the tooth-socket is more elevated than its anterior border. From this description it will be seen that the inner part of the palate rises as a double ridge between the teeth, and in length this ridge is very slightly concave. The sides of the jaw below the teeth round continuously into the inter-alveolar spaces, but they converge inferiorly into a blunt keel. The side below the alveolus is twelve millimetres deep in front, and increases a little in depth behind. It is gently convex and appears to be impressed in the lower part by the longitudinal groove which is parallel to the base. It is about half a centimetre from the base on the right side, and a little higher and less distinctly marked on the left side, especially in front. But for the convexity of the surfaces above and below, I should have regarded it as the result of fracture. Opposite the third pair of tooth-sockets are two holes with impressed borders apparently due to teeth of a flattened character, such as those of a Pycnodont fish. The larger of these impressions is seven millimetres long. The outer layer of bone is a good deal scaled off 1 The tooth-sockets are not uniformly of the same size. The earliest of the four is the smallest, and the fourth is smaller than the third. The second socket is 7 millimetres in length and 4 millimetres in width. The teeth appear to have been directed as usual upward, inward and a little forward.

http://journals.cambridge.orgDownloaded: 11 May 2016 IP address: 130.130.37.84 Prof. H. G. Seeley—On the Genus Ornithocheirus. 19 from the sides of the specimen. This species nearly resembles the Ornithocheirus Sedgwicki of Owen, but differs in the less depth of the jaw, the greater height of the inter-alveolar palatal ridge, the much narrower palatal groove, and the greater distance between the tooth-sockets. It resembles that species in having the tooth-sockets in pairs opposite to each other, in the ovate form of the sockets, and in the compressed aspect of the jaw, though the inferior keel in this species is much more rounded. In the Pterodactylus Cuvieri, the lower jaw of which has not been figured, except in an anterior fragment (plate xii. fig. 5, Ornithosauria), the jaw entirely wants the slender dagger-like shape. One of the most distinctive bones of the skeleton of Omithoclieirus is the scapula. In many other Ornithosaurs, such as Dimorphodon, the bone has a very avian aspect, but in this genus its form, though thoroughly distinctive, perhaps rather suggests the Crocodile, and as Mr. Reed's collection contains one of the most perfect specimens of this bone which I have seen from the (Plate I. Figs, la, 16), I by his kindness append a short note upon its characters. The extreme length of the specimen from proximal to distal end is about nine centimetres. It is best preserved on the internal side, which is concave in length. The proximal end is expanded, and shows a small portion of the articular surface, but the bone there is a good deal decomposed, and all trace of its union with the coracoid, probably sutural, is obliterated. The bone also expands a little at the distal end, and the middle of the shaft, which is compressed and constricted, somewhat thickens distally. The bone terminates distally in a broad oVate flattened surface, which is smooth and moderately convex in length. The out- line is rounded on the coracoid side, and compressed on the posterior margin. The extreme width of this end is about two and a half centimetres, and where thickest is about one and a half centimetre through. This surface is at right angles with the concave side of the shaft. In its most constricted middle portion the width of the shaft is about fifteen millimetres, and its thickness from the com- paratively flattened under side to the more convex outer side is about twelve millimetres. The proximal end of the bone terminates in a large rhomboid mass, which is somewhat cup-shaped on the inner side. Its extreme width is about four centimetres. It is broken on both sides of the median articular surface, which is a little concave in length, and measures one and a half centimetre. Its transverse IBeasurement is about seven millimetres, and in this direction is (Jttovex. The fracture on the outer side is probably small, since more jSWtfect specimens show the bone here to terminate in a founded and compressed tuberosity not greatly different in outline from that indicated by the fossil. The long fracture on the side towards the coracoid, which measures about two centimetres in length, may have removed a small portion of the bone. The lateral outline of the shaft posterior to this fracture on the coracoid side is deeply concave proximally and nearly straight towards the distal end. The corre-

http://journals.cambridge.orgDownloaded: 11 May 2016 IP address: 130.130.37.84 20 Rev. 0. Fisher—Oblique and Orthogonal Sections. sponding posterior outline is more evenly concave. The posterior side is compressed into a nearly straight ridge, which runs along the concave margin of the bone. EXPLANATION OF PLATE I. FIG. la.—Internal surface of scapula of Ornithocheirus; the figure is placed at the proximal end, towards the coracoid margin. ,, 1b.—Superior margin of the same specimen. ,, 2a.—Lateral aspect of lower jaw of Ornithoeheiruaxyphorhynchus. „ 2b.—Palatal aspect of same specimen, showing tooth-sockets. ,, 3a.—Anterior termination oi snout of Ornithocheirus Beedii, seen from the front. ,, 34.—Lateral aspect of same specimen, showing ,(p) (Ck.) fragments of teeth. All figures of the natural size.

III.—OBLIQUE AND ORTHOGONAL SECTIONS OF A FOLDED PLANE. By the Rev. 0. FISHEE, M.A., F.G.S. TN the tenth volume of this MAGAZINE, a correspondence appeared JL upon the subject of "True and Apparent Dip," which was started by Mr. Penning, and continued by several able geologists. The object of the present artiole is to call attention to another branch of the same subject. We are all acquainted with " Sopwith's Models," in which are experimentally shown the outcrops, or " traces," of plane strata upon variously curved surfaces. We now are about to refer to the outcrop of curved strata upon a plane surface. I was led to examine this question from the following circumstances. Professor Prestwioh, a few weeks ago, was so kind as to show me a very typical instance of the superficial deposit which I call " trail," in a railway cutting now iu progress of construction near Chevening', in Kent. The cutting is in Gault, and the trail appears as coarse subangular flint gravel, unstratifled, impacted in a brownish-red matrix of sandy clay, which is very similar in composition to the " clay with flints," which generally covers at a far higher level the upper parts of the North Downs. This trail, as seen in the E. and W. railway section, showed pockets sometimes four or five feet deep, and having a general oblique trend all in one direction. The natural conclusion, on a oursory examination, was that some superficial horizontal pressure acting from W. towards E. had given them this uniformity of trend. But upon viewing the sections on the south bank from the north, it appeared that the trend was exactly opposite to that of the sections on the north bank when viewed from the south. This fact, at first sight, seemed anomalous. But after a little consideration Professor Prestwich suggested to me the true explanation. The oblique trend is not necessarily real, but apparent only ; and is oaused by the obliquity between the direction of the furrow of trail and of the inclined plane which cuts it. We had a model made in wood, and found that a furrow, whose orthogonal section was semicircular, gave an obliquely placed loop upon the face of the cutting plane. Of course this might have been foreseen ; because it is well known that the oblique section of a

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