A NEW RESTORATION OF TRICERATOPS, WITH NOTESON THE OSTEOLOGY OF THE GENUS.By Charles W. Gilmore,Associate Curator, Division of Paleontology, United States National Museum. INTRODUCTION.The life appearance of Triceratops has been depicted by numerouspaintings and by at least three model restorations. During the yearsthat have passed since most of these restorations were prepared, thediscovery of many new specimens and especially of well-preservedskin impressions has added greatly to our knowledge of the probablelife appearance of the horned dinosaurs. The accompanying pho-tographic reproduction, made from a recently prepared model, aimsto embody all of the evidence of recent discoveries and also to expressmy conception of this animal in the flesh. (See pi. 3.)The model is based upon the mounted skeleton^ in the UnitedStates National Museum made to one-fourteenth the linear dimen-sions of the original skeleton. It will be noticed that the head isquite different from the skull on the skeleton and in explanationit should be said that the skull and lower jaws on the mountedspecimen pertain to a different individual than the axial and appen-dicular portions, but that with the latter was found a single largehorn-core which was identified by the late Mr. J. B. Hatcher asresembling the horn-cores of Triccratops elatus Marsh, and on ac-count of that resemblance, I have selected the skull of that speciesas the basis for the head in the present model.The nonimbricating, scalelike texture of the skin as representedin the model is based, with modifications, upon the recently dis-covered Ceratopsian remains in the collections of the Canadian Geo-logical Survey, at Ottawa, with which well-preserved skin impres-sions were found.^ Although these skin impressions pertain to oneof the more primitive Ceratopsians it is quite reasonable to expectthat all of the horned dinosaurs had a scaled integument, though 1 Gilmore, Charles W., Proc. U. S. Nat. Mus., vol. 29, 1905, pis. 1 and 2, pp. 433-435.a Lambe, L. M., Ottawa Naturalist, vol. 27, 1914, p. 132, pi. 14.Proceedings U. S. National Museum, Vol. 55?No. 2260.62055?20?Proc.N.M.Vol .55 8 97 98 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 55.the pattern of the scales may have varied considerably in the differ-ent genera, as they are known to do in the various Trachodont genera.Since this model was prepared in 1915, a second Ceratopsian speci-men (type of Monoclonius cutleri Brown) having impressions of theskin preserved has been discovered. According to Brown ^ thepolygonal scales extended down over the belly, instead of the smallrounded scales here represented as covering those parts in the model,but, of course, we can not be certain that the same arrangement ofthe scales prevailed in the genus Triceratops.One other noticable departure from earlier restorations is in free-ing the femoral part of the hind limb from the flank, thus adoptinga reptilian form of limb, rather than the mammalian form pre-viously used.Future discoveries may show many features of the present restora-tion to be incorrect, but at the least it graphically portrays some ofthe discoveries made during the past 10 years, in our knowledge ofthe probable life appearance of these huge-headed reptiles now solong extinct.NOTES ON THE OSTEOLOGY OF TRICERATOPS.The entire collection of vertebrate fossils, in the United StatesNational Museum, from the Lance formation of Wyoming has nowbeen prepared for study and exhibition. This collection, made by thelate J. B. Hatcher and his associates during the years 1889 to 1891,formed a part of what is known as the "Marsh collection" trans-ferred to the Museum by the United States Geological Survey.In the course of this work, specimens were found which contributeto a better understanding of the osteological structure of certainmembers of the Ceratopsia, and especially important was the uncov-ering of additional bones pertaining to the type-specimens on whichTriceratops ohtusus Marsh and Triceratops calicornis Marsh werefounded.Notes relating to the more important of these specimens are givenin the following pages.THE TYPE-SPECIMEN OP TRICERATOPS OBTUSUS MARSH.The tj^pe of this species as enumerated by Hatcher ^ in 1907, con-sisted of " a pair of mandibular dentaries and the anterior portionof the nasals, a left maxillary, a squamosal parts of a pterygoid, anda vertebra." The finding of nearly the entire remaining partsof the skull (see pi. 4) is a welcome addition to the above material, 1 Bull. Amer. Mus. Nat. Hist., vol. 37, art. X, 1917, p. 299, pi. 18.* The Ceratopsia, Monograph 49, U. S. Geological Survey, 1907, p. 140. NO. 2260. ^-EW RESTORATION OF TRWERATOPS?GILMORE. 99and it now places the type on an adequate foundation for comparisonwith the other and better known species.Although somewhat distorted latterly by pressure the skull isessentially complete, lacking only the rostral, premaxillary bones, andthe median portion of the frill or demosupraoccipital.That the skull belongs to the same individual as the type is shownby the similarity of the labels accompanying both, by the unusualbright yellowish color of the bones and also by the finding of frag-ments with the skull that fitted the dentaries, and fragments with thenasals and dentaries that were fitted to the skull.The original description by Professor Marsh and the more recentdescription by Hatcher are given in their entirety below : Professor Marsh described this species as follows : A second new species, which may be called Triceratops ohtusus, is representedby a large skull belonging to the same genus. The nasal horn core of this skullIs very short and obtuse and so well preserved that it indicates the normalform and size. The entire length of this horn core is only 1 inch. Its summitis Si inches behind the premaxillary suture. The width of the nasals beneaththe horn core is 5^ inches. The length of the squamosal from the quadrategroove to the posterior end is about 36 inches and its greatest width is 19 inches.These two skulls [types of T. calicornis and T. obtusus] were both found byJ. B. Hatcher in the Ceratops beds of Converse [Niobrara] County, Wyo.Hatcher redescribes the specimens in the following : The type (No. 4720, U. S. National Museum) of the present species consistsof a pair of mandibular dentaries and the anterior portion of the nasals, a leftmaxillary, a squamosal, parts of pterygoid, and a vertebra. The specific namewas suggested by the nasal horn core. The nasals, as shown in the accompany-ing figures, are extremely broad, and the nasal horn core is reduced to a broad,rounded, and rugose prominence, marked with a number of deep vasculargrooves.The dentary is exceptionally deep and the teeth are unusually large. Belowthe base of the coronoid process on either dentary the external surface of thebone presents a very sharp ridge that extends continuously throughout aboutone-third of its length. The posterior portion of the alveolar region of the leftdentary bears evidence of having been affected by disease and presents extensivemalformations. The mandibular fossa extends rather farther forward than iscommon in other species of the Ceratopsia. The dentary is exceptionally mas-sive and the teeth are very large. There are a number of foramina on theexternal surface of the dentary, as shown in the accompanying figure.Notwithstanding the scanty and fragmentary material upon which the presentspecies is based, it would seem to be a valid one, as indicated alike by thecharacters of the dentary, the teeth, the nasal horn core, and that part of thenasals still preserved.The type of tlie present species was found in Converse [Niobrara] County,AVyo., about 1 mile east of Lance Creek and 2 miles southeast of the U-L ranch.The horizon would be about the middle of Laramie [Lance], as those depositsare represented in this region. The locality is shown at +9, PI. LI. 100 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.55.Principal Measurements of the Type-Specimen. mm.Greatest length of dentary G70Greatest depth of dentary 229Length of dental series 535Breadth of nasals at base of horn core 140Distance from top of nasal horn core to inferior surface ofnasals 75I have been unable to find in the collections of the U. S. National Museumthe squamosal mentioned by Marsh as pertaining to the type, and can saynothing concerning the form of this important element. The other portionsof the skeleton preserved show no peculiarities vporthy of note.The missing squamosal mentioned by Hatcher was found in oneof the recently opened boxes. The left squamosal, lacking the pos-terior end (see pi. 4) , was attached to the skull. Although Hatchercollected this specimen, the presence of nearly the entire skull hadobviously entirely escaped his memory, as no allusion is made to itin any of his writings. The characters pointed out by Hatcher fordistinguidiing this species are for the most part of a trivial natureand little dependence can be placed on them as representing con-stant specific differences. The peculiarities found in the dentariesmay be attributed in a great degree to the severe crushing whiclithese bones have undergone, in addition to the malformations in theleft element to which Hatcher calls attention. A comparison of thedentaries with others in the collection of the United States NationalMuseum fails to disclose any great degree of difference in the for-ward extension of the mandibular fossa, its apparent extensionbeing due to the absence of the overlying splenial and to deforma-tion of the bone by vertical pressure. The width of the nasals alsoappears to have been exaggerated by crushing. Of the specificcharacters pointed out by Hatcher, the reduced nasal horn corealone is probably valid, though it may be only a sex character.The supraorbital horns as compared with the types of T. calicomisMarsh and T. elatus Marsh are somewhat shorter and lack the greatforward curvature. They are not quite as stocky as those of T.hrevicornus., which they resemble most nearly in a lateral view.After a careful comparison of this additional material of T. ohtususwith the several types in the United States National Museum collec-tions, and with the figures and descriptions of other species of thegenus preserved elsewhere, I am unable to detect characters thatwould satisfactorily distinguish this species.In the present accepted classification of the Ceratopsia, and es-pecially of the species of the genus Triceratojys^ great importance isattached to the development of the nasal and supraorbital horncores, and the peripheral outgrowths of the frill. It is not yet clearhow much dependence can be placed on the differences found in thesehorns, or their almost complete absence as in T. obtiistis. There is NO. 22G0. NEW RESTORATION OF TRICERATOPS-GILMORE. 101great variation, as might well be expected in such highly specializedoutgrowths, and the differences in sex, and stage of growth presentother features that have also to be considered before a satisfactoryconclusion can be reached as to what characters constitute valid spe-cific differences. In fact, the whole group needs restudying. Sucha revision assisted by the considerable number of new specimensdiscovered since the writing of the Ceratopsia monograph in 1907may enable an investigator to straighten out this confusion. At thepresent time it appears quite certain that the number of describedspecies is too great by a considerable number.THE TYPE-SPECIMEN OF TRICERATOPS CALICORNIS MARSH.At the time of writing the Monograph on the Ceratopsia, Hatcher^and Lull mentioned their inability to locate in the collections of theUnited States National Museum the lower jaws pertaining to thetype-specimen of THceratops caliconiis Marsh, No. 4928, U. S.N. M. Upon opening a large box, listed as containing theskull of another individual in it was found the long misplaceddentaries. These are in an excellent state of preservation. In thesame block of sandstone with the lower jaws was a posterior cervicalvertebra and portions of several thoracic ribs.The vertebra is from the posterior part of the neck and representsthe seventh of the series counting backward from the skull, or itbelongs behind the first of the series as illustrated in figure 2, plate40, of the monograph cited above. Figure 2, Plate 5, shows thisvertebra inserted in its proper position in the vertebral series. Thatthis is the correct position of this element in the vertebral column isclearly shown by the shape and length of the transverse processesand also by the perfect articulation of the zygapophyses.The dentaries except for their great size are similar to those ofother described species, and the few minor differences observed do notadd anything to the diagnosis of the species.The principal measurements of the dentaries are: mm.Greatest lengtli 045Greatest depth 170Length of dental series 480In the left ramus there are 38 rows of teeth in the dental maga-zine.The type-specimen now completely assembled consists of the fol-lowing parts : Skull, lacking some parts of the frill, lower jaws, 2 cervical verte-brae (portions of atlas and other cervicals), 10 dorsal vertebrae (por-tions of other dorsals), 5 cervical ribs, 2 thoracic ribs (many parts 1 Monograoh 4".). U. S. Geological Survey, 1907, p. 139. 102 PROCEEDINGS OF THE NATIONAL MUSEUM. vou55.of others), both pubes, both ilia (poorly preserved), sacrum (poorlypreserved), and many ossified tendons.CERATOPSIAN VERTEBRAE.In plate 5, figure 1, is shown an articulated series of eight pos-terior dorsal vertebrae (No. 8091, U.S.N.M.), collected by Messrs.J. B. Hatcher and A. D. Sullins in 1891 on Schneider Creek, Nio-brara County, Wyoming. These vertebrae are notable for their finestate of preservation and that they are from that part of the columnof which but little is known at the present time. This series pertainsto a member of the genus 2'riceratops, but the species has not yetbeen determined.A DISEASED CERATOPSIAN SCAPULA.In plate 6, figures 1 and 2, is shown two views of a Ceratopsianscapula, of the right side belonging to the genus Triceratops, whichis of interest on account of the presence on the internal side, of anotherwise normal bone, of a large bony hornlike growth. Fossilbones are often found, and especially of the horned dinosaurs, show-ing fractures that have healed in life (see pi. 9) usually with aconsiderable enlargement at the point of fracture, but in the presentspecimen there is no evidence of the bone having been fractured,though this horn-like projection is doubtless an exostosial growth dueto pathologic conditions. That it must have been very uncomfort-able to the animal, and a serious handicap to the movement of theshoulder blade, is readily apparent.The scapula (No. 8oi3, U.S.N.M.) was collected by the late J.B. Hatcher in 1891 from the Lance formation in Niobrara County,Wyoming.RELATIONSHIPS OF CERTAIN CRANIAL ELEMENTS IN THE SKULL.During the past few years several papers have been written inwhich the homologies of the bones of the Ceratopsian skull and braincase have been discussed in considerable detail. While each authorhas contributed to a better understanding of these elements and theirrelationships there is still a lack of unanimity of opinion regardingsome of them. Certain modifications have led to such a rearrange-ment of the cranial elements that until correctly interpreted are asconfusing as they are unusual. The coossification early in life ofmost of the bones, is another feature that still further adds to thedifficulty of determining their true relationships. A restudy ofspecimens in the United States National Museum in conjunction withtwo Triceratops skulls recently prepared further elucidate the NO. 2260. 2VEW RESTORATION OF TRWERATOPS?GILMORE. 103homologies of these bones and also furnish corroborative evidence insupport of the conclusions reached by me in an enrlier study of ajuvenile skull of Brachyceratops ^ montanensis.In plate 8 is shown a fragmentary skull (Cat. No. 5740, U.S.N.M.)in longitudinal section. It is known by the field designation as Sk. 27, Fig. 1. LOXGITUDINAL SECTION OF SKDLD SHOWING BRAIN CAVITY OF TuiCERATOrS, FROMNo. 5740, U.S.N.M., about one-eighth natural size. B. oc. pr., basioccipital proc-ess ; CAR., foramen for left carotid artery ; D. so., anterior end of dermosupraoc-ciriTAL ; F., POSTERIOR portion of frontal ; Mx., maxillary ; Oc, occipital con-dyle ; p., PARIETAL, it ALSO EXTENDS FORWARD AROUND THE PINEAL FORAMEN TO MEETTHE THICKENED POSTERIOR END OF THE FRONTAL; PIN., PINEAL FORAMEN; PIT. F., PITUI-TARY fossa; pt. f., postfrontal; pt. ff., postfrontal fontanelle ; s. oc, suprv-OCCIPITAL ; v., FORAMINA FOR EXIT OF SUPPOSED VEINS; I, II, III, IV, V, VI, VII, VIII,IX, X, XII, FORAMINA FOR EXIT OF CEPHALIC NERVES OF CORRESPONDING NUMBERS.and was collected by Messrs. J. B. Hatcher and A. D. Sullins, in 1891on Doegie Creek,^ Niobrara Countj' (formerly Converse County), 1 1'rofessional Paper lO.*?, U. S. Geol. Survey, 1915.?In plate 4n of Monosiaph 40. TJ. S. Orolosical Survey, 1907, Sk. 27, Is indicated onthe map as having been found on Bull Creek, but in figure 53 (p. 207) of the Dinosaursof North America this? same stream is designated Doegie Creek, which agrees with theoriginal lalxi found with the specimen. The former is probably an error made in trans-scribing the legends on the map. 104 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 55.Wyoming. On account of the absence of all the essential externalportions such as the horn-cores, nasals, premaxillaries, and most ofthe squamosals, I am unable to determine the species to which thisspecimen belongs. It serves, however, to graphically illustrate theinternal structure of the Ceratopsian skull, and especially the rela-tively small size and position of the brain cavity, and the large over-lying sinuses.A study of this sectional skull in conjunction with the posteriorportion of the cranium of a second individual (Cat. No. 6679,U.S.N.M. ; see Plate 7.) Triceratops species, and the disarticulatedskull of Brachyceratops 7nontanensis (Cat. No. 7951, see fig. 4) en-ables me to verify the work of other authors and in some instances topoint out where they were in error. Commencing with the frill I thinkall authorities are agreed that the lateral bones are the squamosals.It is the median part of the frill that has been the subject of muchdiscussion and a variety of interpretations. Marsh first identified itas the fused parietals, and he has been followed by most writers onthe subject. Hay^ showed that this identification could not be ac-cepted and suggested that it might represent the fused supratem-porals or possibly the coalesced nuchal bones. Huene ^ identified theanterior end of this central portion as parietal and the posterior endas a dermosupraoccipital, but it has been pointed out that this con-clusion is not altogether acceptable. Gilmore^ in describing theskull of Brachyceratops reached the conclusion that the parietal wasentirely excluded from the dorsal surface of the skull in that genus ? a conclusion verified by Brown * in a later study of other Ceratopsiamslmlls. In the article cited above Brown also concludes that themedian part of the frill represents the " fused postfrontals." Thestudy of the disarticulated Brachyceratops skull which has the post-frontal bones entire (see fig. 4), shows conclusively that they do notextend backward to form any part of the crest. In fact a compari-son of the top of the Brachyceratops skull with a Monoclonius skull,figured by Brown ^ shows a transverse line between the supratem-poral fossae, separating their posterior ends from the frill portionas in Brychyceratops although it is not there recognized as a suture.That a suture does exist at this point is abundantly shown by sev-eral skulls and numerous separate frills. That the conclusion reachedby both Gilmore and Brow^n that the parietal does not show on thedorsal surface of the skull is further substantiated by specimensNos. 5740 and 6679, particularly the latter, which shows the parietalas extending upward and backward as a thin sheet of bone under-iProc. U. S. Nat. Mus., vol. 36, 1908, pp. 95-108.sNeues Jahrbuch, vol. 11, 1911, pp. 146-162.? Smiths. Mihc. Coll., vol. 63, No. 3, 1914, p. 7.* Bull. Amer. Mus. Nat. Hist., vol. 83, October, 1914, p. 543.? Idem, vol. 34, October, 1914, pp. 549-558, fig. 1. NO. 2260. :sfEW RESTORATION OF TRICERAT0P8?GILM0RE. 105lapping the forward part of the dermosiipraoccipital to which it isclosely applied, by squamous suture, thinning out to a thin edgealong the line indicated in s. plate 7. From a posterior view Huenedepicts the lateral extent of the parietal quite clearly in fig ire 2 ofthe paper cited above, and Brown also shows its more limited develp-ment in the genus Monoclonlus. (See fig. 2, Bull. Amer. Nat. Hist.,vol. 33, 1914, p. 555.)All writers are agreed as to the position of the postfrontals asbeing immediately in front of the dermosupraoccipital (called parie-tal, postfrontals, supratemporals, etc.) bone, but there is much dis-S.or. "Jif.S/t- FiG. 2. ? Longitudinal section of brain case of Tkiceratops serratds Marsh No.2416, U.S.N.M. About one-third natural size. a. c. f., anteuiou condyloidforamen ; Al. sp., alisphenoid ; B. oc, basioccipital ; B. oc. pe., basioccipitalprocess; car., foramen for left carotid artery entering pituitary fossa; car. g.,groove for eight carotid artery ; ex oc, exoccipital ; f., extent of the articu-lation of the frontal with the underlying orbitosphenoids ; 0c? occipitalcondyle; Or. bs., orbitosphenoid ; O. po., paraoccipital process; pit. f., pituitaryfossa; Pro., prootic ; S. oc, supraoccipital ; T. m., foramen magnum; v.,foramina foh exit of supposed veins ; I, II, III, IV, V, VI, VII, VIII, IX, X, XII,foramina for exit of corresponding cephalic nerves.agreement as to the extent of these elements. Marsh, Hatcher, Lull,Brown, and Lambe considered the postfrontal as including nearlyall of that portion of the skull between, and including the horn coresand an area on the lateral surface extending down and back of theorbit to its inferior level. Huene correctly recognized a portion ofthe lateral area posterior to the orbit as being the postorbital and soit stood until the discovery of the Brachycerato'ps skull which dem-onstrates conclusively that the postorbital in that genus includes thehorn above the eye and that the lateral extension of the post frontalsis not external but internal to the supraorbital horn cores, as shown 106 PROCEEDINGS OF THE NATIONAL MUSEUM. TOL. 65,in figure 4. I can hardly believe, in the light of the Brachyceratopsskull, that the postorbital bone has been so reduced in size in Tricera-tops as indicated by Huene. In a recent paper by Lambe ^ the smallbones interposed between the prefrontals and identified as the fron-tals represents without question the forward ends of the postfrontals.The frontals, as pointed out by Huene,^ do not appear on thedorsal surface, but are excluded from that view by the overlying pre-frontals (the lachrymals of Huene). Figure 6 shows a longitudinalsection of the skull of Triceratops -fiabellatus Marsh after Lull where ., /Sor. .^.?g r.of/if /' " '/ W. -M s^i.Orbs jSec-Fig. 3. ? Sdperioh view of brain case of Triceratops serratus MabsHj No. 2416,U.S.N.M. Abodt one-third natural size. Al. sp., alisfhenoid ; B. oc, basioc-ciPiTAL ; B. oc. PR.^ basioccipital process ; Ex oc, ExocciPiTAL ; F., showing ex-tent of THE articulation OF THE FRONTAL WITH THE UNDERLTIXG ORBITOSPHEXOIDS ;fm., foramen magnum; oc, occipital condyle; o. po., paraoccipital processes;Or. bs., orbitosphenoids ; Sec, line indicating point of separation of twohalves of brain case, of which a section is shown in fig. 2 ; s. oc, supba-occipital.the frontal = prefrontal + postfrontal) is indicated as having aninferior branch directed downward and backward from the nasalsto the anterior part of the brain case. This lower branch representsthe true frontal as is clearly shown by the juvenile Brachyceratops ^skull in which the overlying pre- and postfrontals exist as distinctelements. A study of the sectioned skull (No. 5740, U.S.N.M.)plate 8 and text figure 1 now enables me to definitely determine forthe first time the posterior extent of the frontals, as being the thick-ened bone immediately overlying the olfactory lobe of the brain, ^ Museum Bull. No. 12 Canada Department of Mines, pi. 9,?Neues .Tahrbuch, vol. 11, 1012, fig. 1.s See Prof. Paper 103, U. S. Geol. Surv., 1917, p. 10, fig. 6. 1, 2, 1915. NO. 2260. tJEW RESTORATION OF TRICERAT0P8?GILM0RE. 107 see F^ figure 1, and extending back to the pineal foramen, see pirijfigure 1. In the great thickening of the bone and its relationship tothe brain and underlying structure, it closely resembles the frontalof Diplodocus longus Marsh as shown in figure 5, Fr. In specimenNo. 5740, U.S.N.M., the sutures are almost entirely obliterated, butO M ^ IB W ?A " g !5 E S W& 9 a 'i^ a w J aM ^M S O ?? S ft W f, w "5 a, -d & S S m o 2 w d t" Z 'j - ^ca a ^ q <5 in a second brain case of Triceratops serratus Marsh (No. 2416,U.S.N.M., see figs. 2 and 3) the olfactory lobe is entirely inclosedby what Hay regarded, and I believe correctly, to be the unitedorbitosphenoids. Such a condition is unusual, for in no other rep-tile living or extinct have I observed these bones thus inclosing thispart of the brain. Usually the frontal forms the median upperboundary and I presume such a condition will be found to prevail 108 PROCEEDINGS OF THE NATIONAL MUSEUM. tou 55.in most Ceratopsian skulls. In fact, in specimen No. 5740 U.S.N.M.,a longitudinal ridge, that may represent a coalesced suture, runs alongthe inside of the wall of the brain case for the olfactory lobe and ifcorrectly interpreted shows that the frontal did contribute to theupper boundary of this part of the brain. By comparing speci-mens Nos. 6740 and 2416 it was possil^le to determine the exactextent of the articulation between the frontals and the underlyingsutural surfaces of the orbitosphenoids in No. 241G, as indicated infigure 3, F. It will also be noted that these sutural surfaces con-tinue backward over the superior surfaces of the alisphenoid andsupraoccipital bones, thus entirely surrounding the large medianopening above the cerebrum lobe of the brain. This aperture asshown in figure 3 is larger than it would be normally as all of theborders present broken edges. The question now arises, what bonearticulated with these sutural surfaces? After a study of manyreptilian skulls both recent and extinct it is found that the parietalis the only bone that fills all requirements. As in other reptilianskulls it here articulates anteriorly with the frontals ; ventrally withthe supraoccipital, alisphenoids, and in all probability also with theprootic. Furthermore, specimen No. 5740, U.S.N.M., shows thatimmediately behind the thickened rounded posterior end of thefrontal is a well-defined median foramen leading from the braincase into the large air chamber above (see pin. fig. 1), and repre-sents without question the interparietal or pineal foramen. Theposition of this foramen on the median line and near the suturalunion of the parietal and frontal, and largely if not entirely withinthe former bone, is in entire agreement with the location of thisforamen, in Dlplodocus see /. pin.^ figure 5, the living Hatteria, and inthe Ichthyosauria and Plesiosauria. The large air chamber or sinusinto which the pineal foramen opens, extends upward into the baseof the large horn cores with an external outlet through an openingat the junction of the postfrontals with the dermosupraoccipitalsee pt. f. f. figure 1. This opening has been designated pineal fora-men by Marsh ; " the postfrontal foramen," by Hatcher ; the " post-frontal fontanelle," by Lull and Lambe ; the " supratemporal fossae,"by Hay; and the " pseudopineal foramen," by Huene. The term " postfrontal fontanelle" is perhaps the more appropriate designa-tion for this opening rather than " postfrontal foramen " the use ofAvhich was advocated in my study of the Brachyceratops ^ skull forthe reason that it represents an opening not yet roofed over by bone,or, in other words, the coalescence of the postfrontals with oneanother and with the dermosupraoccipitals which had begun in theearliest known Ceratopsians had not been perfected, except in oldindividuals belonging to the last we know of the race.iProf. Paper 103, U. S. Geol. Survey, 1914, p. 18 NO. 2260. ]^EW RESTORATION OF TRICERAT0P8?GILM0RE. 109Specimen No. 5740 shows that portion of the parietal around thepineal foramen and extending upward above the supraoccipital tohave been very thin on the median line. Whether it becomes heavierlaterally can not be determined, but higher up it widens perceptiblyprovided all of the bone is parietal, but it again thins out into awide sheet of bone that underlaps the dermosupraoccipital as shownin plate 7, P. as has been previously described.f^Fr. i/^ftf- .S.oc,\ \^S end as/).? '^\ tio.694AM. "tui.B. oc {b's[>.)Fig. 5. ? Longitudinal section of skull of Diplodocus longus Marsh, No. 694,Ameh. Mds. Nat. History. One-half natural size. B. oc, basioccipital ;B. ft. pk., basipterygoid processes; B. sp., basisphenoid ; car. in., foiiamen fobEIGHT CAROTID ARTERY; Ex. OC. EXOCCIPITAL ; F. PIN., PINAL FORAMEN; FR., FRONTAL;0. SP., ORBITOSPHENOID ; Pa., PARIETAL ; PIT. FOS., PITUITARY FOSSA ; PE. OT.,PBOOTIC ; ?P. SP., PRESPHENOID ; S. END., SACCUS ENDOLYMPIIATICUS,* S. FC, SUPRA-OCCIPITAL ; TUB. B. OC, BASIOCCIPITAL TUBEROSITY ; I, II, III, IV, V, VI, VII, IX, XI,XII, FORAMINA FOB EXIT OF CORRESPONDING CEPHALIC NERVES. (AFTER OSBORN.)In figure 2 S. oc, the supraoccipital is indicated as extending fromthe top of the foramen magnum to the sutural surface above theforamen for the exit of the IV nerve. Hay in figuring this samespecimen ^ regarded only the lower or posterior half as supraoccipital, ? See Proc U. S. National Museum, vol. 36, 1909, pi. 2, fig. 1, 110 PROCEEDINGS OF THE NATIONAL MUSEUM. VOL. 5&.the upper or anterior half the parietal. Their junction being indi-cated by the foramen at the extremity of the left cerebellar process.*Brown in discussing the brain case of Anchice7'atops and of a Tracho-dont dinosaur ^ regards this same point as being the position of thesuture between these two bones. In none of the specimens discussedabove can a suture be detected at this point, and the presence of asutural surface on the upper end of the bone here called supraoccipital(see s. oc, fig. 3), seems to me to clearly indicate the forward extentof this bone to be as shown in figure 2, S. oc. Fig. 6. ? Longitudinal section of skull of TuicERArors flabellatus Marsh, fromNo. 1821, Yale University Museum. One-sixteenth natural size. Bo., basi-OCCIPITAL ; D., DENTARY ; EXO., EXOCCIPITAL ; FR., PRE- AND POSTFEONTAL (FRONTAL OFLull) ; h., postobbital horn core ; mx., maxillary ; nas., nasals ; nh., nasal hornCORE ; NO., nasal opening ; pa., dermosupraoccipital (parietal of Lull) ; pd.,prbdbntary ; pf., fostfrontal; pl., palatine; pmx., premaxillary ; q., quadrate;K., rostral; so., supraoccipital; sq., squamosal; n., sinuses beneath postfrontalbones; xo., postfrontal fontanelle. (After Lull.)SUMMARY.The principal facts now established from the latest study of theCeratopsian skull and brain case are : 1. The presence in Triceratops of a well-defined pineal foramen.2, That neither the frontals nor parietals are visible from a dorsalview of the skull. * This foramen appears to go entirely through the bone in specimen No. 2416, shownIn figure 2, but In No. 5740, although there Is a deep pit, see v, figure 1, It appears notto reach the outer surface.* See Bull. Amer. Mus. Nat. Hist., vol. 33, 1914, p. 547. NO. 2260. 2^EW RESTORATION OF TRICERATOPS?GILMORE. Ill 3. That the prefrontals and post frentals which in the normalreptilian skulls are lateral elements have in the Ceratopsian craniumshifted their position from a lateral to a dorsal position supportedbeneath by strong vertical buttresses. That such a change has takenplace is further indicated by the fact that in the older and moreprimitive Ceratopsians the complete coalescence of the post- andprefrontals of opposite sides on the median line has not always beenperfected, though I know of no Lance specimens where this completecoalescence has not been completed.After a study of the brain case in Camptosaurus, Stegosaiirus,TraeKodon^ Allosaurus^ and Triceratops it appears that no matterhow diverse the modifications of the external bones of the skull maybe, those forming the brain case have the same definite relations toeach other and to the brain itself. Lambe considered the postfrontalas including nearly all of that portion of the skull betweenthe horn cores and an area on the lateral surface extendingdown and back of the orbit to its inferior level. Huene correctlyrecognized a portion of the lateral area posterior to the orbit as beingthe postorbital and so it stood until the discovery of the Brarhycera-tops skull which demonstrates conclusively that the postorbital inthat genus includes the horn above the eye and that the lateral exten-sion of the postfrontals is not external but internal to the supra-orbital horn cores, as shown in figure 4. I can hardly believe, in thelight of the Brachyceratops skull that the postorbital bone has beenso reduced in size in Triceratops as indicated by Huene. In a recentpaper by Lambe ^ the small bones interposed between the prefrontalsand identified as the frontals represented without question the for-ward ends of the postfrontals.EXPLANATION OP PLATES.Plate 3.Life restoration of Triceratops elatus Marsti. Modelled by Charles W. Gil-more 1915. Based on the mounted skeleton in the United States NationalMuseum, About one-twenty-eighth natural size.Plate 4.Skull and jaws of Trirrrnlnps ohtn.ttts Marsh. Type. No. 4720, U.S.N.M.Viewed from the left side. About one-twelfth natural size.Plate 5.Fig. 1.?Series of eight articulated posterior dorsal vertebrae of Triceratops,sp. No. 8091, U.S.N.M. About one-eighth natural size. Viewed from the rightside. The transverse processes of the left side are perfectly preserved. * Museum Bulletin No. 12, Canada Department of Mines, pi. 9, figs. 1 and 2, 1915. 112 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.55.Fig. 2.?Cervical and dorsal vertebrae of Triceratops caUcornis Marsh. Type.No. 4928, U.S.N.M. About one-eighth natural size. The second vertebraefrom the left is the posterior cervical found in the block of sandstone with thedentaries and is here shown in its proper position in the vertebral series.Plate 6.Fig. 1.?Right scapula of Triceratops, sp. No. 8013, U.S.N.M. Oblique inter-nal view. Shows the horn-like growth protruding from the inner side of theshaft.Fig. 2.?Same as above. Direct internal view. Both figures about one-eighthnatural size. Plate 7.Posterior view of skull of Triceratops, sp. No. 6679, U.S.N.M. About one-eighth natural size.D. So., dermosupraoccipital ; Ex. oc, exoccipital ; Q., quadrate ; P., parietal ; B., indicates the upper extent of the parietal where it underlaps the dermo-supraoccipital, at this point the two bones are slightly separated, the inter-vening space being filled by matrix.Plate 8.Longitudinal section of Triceratops skull through the center of brain caseNo. 5740, U.S.N.M. About one-eighth natural size. Explanatory drawing ofthis speciment shown in text figure 1.Plate 9.Postorbital horn cores of Triceratops elatus Marsh. No. 4708, U.S.N.M,Viewed from the back about one-eighth natural size. This specimen is ofinterest as showing that the right-horn core was broken off during life, evidentfrom the fact that the stump had healed and rounded over. The size of thehorns and other parts belonging to this specimen indicate they belonged toan old individual.The specimen known by the field designation as " Sk. 11 " was collected bythe late J. B. Hatcher in 1890 from the Lance formation near Buck Creek,Niobrara County, Wyoming. U. S. NATIONAL MUSEUM PROCEEDINGS, VOL. 55 PL. 3 U. S. NATIONAL MUSEUM PROCEEDINGS, VOL. 55 PL. 5 V-K : f * fe " -Ti Vertebrae of Triceratops.For explanation of plate see pages III ? 112. U. S. NATIONAL MUSEUM 1 PROCEEDINGS, VOL. 55 PL. 6 Scapula of Triceratops.For explanation of plate see page 112. U. S. NATIONAL MUSEUM PROCEEDINGS, VOL. 55 PL. 7 ?. ** ? \ D.SQ. Skull of Triceratops.For explanation of plate see page 112. U. S. NATIONAL MUSEUM PROCEEDINGS, VOL. 55 PL. Sectional Skull of Triceratops.For explanation of plate see page 112. U. S. NATIONAL MUSEUM PROCEEDINGS, VOL. 55 PL. 9 Horn Cores of Triceratops elatus Marsh.For explanation of plate see page 112.