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HMUITION mr CMMT 
 
 {AN» and BO TIST CMAIT No. J) 
 
 1.0 
 
 1.1 
 
 iai2.g 
 
 itt 
 
 lu 
 
 m 
 
 IM 
 
 12.2 
 
 Itt 
 
 1:25 lu 
 
 A 
 
 ^^PPLIED IM^lGE l™. 
 
 1MJ CM Moin StrMt 
 
 ^OCtM«t«f. Nm 
 
 (716) 4U - 0X)0 - PKona 
 (716) 2aa-99W-Fai 
 
 Tort- 1*60« USA 
 
^ 
 
 C-r^"OOC 
 
 CA.Hl, L2 U\ CANADA 
 
 DEPARTMENT OF MINES 
 
 SB Jahh Iauobud, Minutik; Cbarum Caii»bu., Dwvtt Mnnma. 
 
 GEOLOGICAL SURVEY 
 
 WnxiAM Mclmnn, DnuBcioB. 
 
 MEMOIR 120 
 
 / 
 
 No. 108, OlOUMIOAL 8s«I18 
 
 The Hadrosaur Edmontosaurus 
 from the Upper Cretaceous of Alberta 
 
 Lawrence M. Lambe 
 
 OTTAWA 
 
 THOMAS UULVBT 
 
 PaiNTBB TO TBS KINO'S MOST BXCBLX.BNT MAJC8TT 
 MM 
 
 MObMM 
 
I 
 
 CANADA 
 
 DEPARTMENT OF .MINES 
 
 8i« Jamm Louoh«d. Mim^tm; Chahlm (AM-.r.tL. I),:,- ,> M,.s,.stkh. 
 
 GEOLOGICAL SURVEY 
 
 WiLLMU McInneh, Director. 
 
 I MEMOIR 120 I 
 
 No. 102, CieoLooicAL Skhies 
 
 The Hadrosaur Edmontosaurus 
 from the Upper Cretaceous of Alberta 
 
 Lawrence M. Lambe 
 
 OTTAWA 
 
 THOMAS MULVEY 
 
 PRINTER TO THE KINGS MOST' EXCELLENT MAJESTT 
 
 1120 
 
 No. IS14 
 
/ 
 
 CONTENTS. 
 
 Iiiiriiiliii'liiiii 
 
 Mittrriiil iiri »|ii<'li I JliiiiinliiMaiirii-i i« IiiihvI 
 
 (><lc<.|(i({v iif Kiliiiixitii- iiirii> 
 
 Skull . . 
 
 Maii.lil.l.' 
 
 • •liter o|HMim;~ ,,t ilir -kill! 
 
 I Irani 
 
 Vrrlilini' 
 
 Itil.s . 
 
 I'ori' liiiili 
 Tlif (t'-nin Kiliiiiiiiii.-.iiini- 
 <'lax'«lli(Miiim of till llailrii-aiiri.la> 
 
 Divi-ioii iiitii iliiif Milil'aiiiili, , 
 
 ('iiiii|>ari-iin with nl iii. | iDrin- 
 I.ii>t iif j>riiici|i.il Hurler nii-.l 
 Iiiik'X. 
 
 Illustrations. 
 
 Hgiirr I. Itiiik- i,f iIk' Kiliiiiiiitori li.riiiaiiuii. lii.l I).,r hm \ll.crli 
 
 .;■ ^"'■„ "' .''»• 'I'>''"V"V I" "'••'•'' "1 ll"' ><<<iM.| •kr|.t..ii ..I !■:, I ,„'„„,„,.„.„„. 
 •f. Skull 111 tyjii' nf h..ln„.,it<.s,iN,u.^ ,,,i,il,.^: I.ii lairril i-i.. n 
 
 ). Suprriiir a>|li( I nf the ~alllr 
 
 •V ('raiiniiii of j-ir: ivpr ,,r /•;«/»,„„/„„;,„■„, ,,,,„l,s; luC rmr vi.« 
 
 ll. I ii!-li riiir view III ijic "aiiir 
 
 7. Aiilrrinr viiw of ilir same .....'. 
 
 S. Su|irrliir virw of the >aliir . 
 
 !t. KiKlit l.rrfri.nlalof paralviirof /,',/,„„„,„.„ „ „.:; vi,.w,.,| Iron. I„.|,.a ,.I,|„m„.. 
 
 Iv Iroiii thr riar ' 
 
 10. liiKlil lacJiryiMal of paralyp.' ol /•;./»»,-■ ..,„„„.v; ..M.rii.al iiitirr.il an.! 
 
 lM»trni>r a.-pcii.< ■■.mi 
 
 11. Hiulit iiaj.al of paralypc of i-:,h,„,„l„.'.i.„ „s: im-riial a-i- ' ..Mi.iu. Iv 
 
 troiu tirlow ' ' ■ 
 
 12. I,..ft Miaxillary of jiaralyiii. of E.iw„„ln.„ „,,.,: ,M,.n:al mimI ml. rn .1 
 
 IlSjM'CtS 
 
 l:i. l..fl iiiaxillaiy, iialatiii.., pt.ryuoi.L aii.l iclnpi.rvtfoi.l ,,( p,r-,n,i,. ,i 
 
 r.'liimnlii.-'iiiinin: ixtiTiial a^^piTt . . ' ■ . i 
 
 Ij. r.,ft jiiKal of p.iralyp,. „f h:,lnu,„l„..,.,r„.- vinvnl froiii williin 
 
 I.«. Left .|ua.lrati,-jUKal of paralyi f H,lm.wl„.„un,-.: out,.. „.V ii-m - 
 
 a>pi'cls 
 
 111. I.i'fl (luadralc of paralv|«' of A,''/ih.,///.,,v,..i„„V;' vicw.il \-\u\ 
 
 from Ihr front, iiiicrnally olilii|ui'h fidin ih.. rcir 
 
 tran>viT.<i> H'clion.^j 
 
 17. I,rft ptiTyttoiil of iiaratyp.' of A',/,,,,,,,^;^,,,,,.,,.; ..viiTiial an,| it.i.Tii.l 
 
 uspcci s 
 
 IS. HiKlii palalinrofparaiyp,. of 'aV,,;,;^^wp,;,,,:;, ,,,,,.,.,,,, li,,,,,,,.^,,, 
 
 I. . I.o t .riopl,.ryK,„.| • . paraty ,f /•;,/„,„„/„..„„,„..; ,„„„,. ;„„, i„„„,.'„,, ,,,, 
 
 ... \V '."■""'''•"I'll- '•■"■"1* "I p.ii-alyp,. of /■:.l,„n„i,,.„„r,is; iunrr a«p<rl 
 -I. Loft iloiilary ol p;iratyp,. of /.•,/,„„„^,.„ ,/•./,. : inn.r avp,c( 
 — KlUlit siii,.nK„l:„. ,,f ,,;,ralyp,. of Kiim;>,l„s„„r„:<.- iMrnial ii.Ii-rnil ,ihI 
 superior a-pei'ts ' 
 
 Zi. Tortionof left arlieular of parutypeor/i:/,„,„:/„;„;;„-;,.;„x„;niai; anterior 
 
 ami posterior a.^jieiMs 
 
 24. I,ef, splenial of par,.ly,,e of K,lm,.nl.,.„,n,:; outer an.l inner views ' 
 -. . iKht aiiKular of paratype of y..,/,„„„M.,„.,„..; o-.ter aiel inner views 
 -J). Itrain-ease of paratype of '•,,/,„„„/,,.,„„•„.; ri^lit laler.,1 aspeet 
 ... < ast ol l.rail.-e.ivity of paratype of lC.lm,mt„^„„n,'<; left lateral, slip ■ 
 
 ly olilii|u. I-. 
 II oiitlaii-- 1. 
 
 (•> 
 
 ."ll 
 
 •"i7 
 
 t.i 
 •hi 
 
 liO 
 
 •17 
 •i7 
 t'.s 
 77 
 7!l 
 
 I 
 
 tl 
 
 !» 
 II 
 I I 
 Is 
 
 :iu 
 
 i:i 
 It 
 I.-. 
 
 and inferior aspeets 
 
 p Tior. 
 
 «2.i— 1 i 
 
 s 
 4 
 
I 
 
 7K 
 
 ;n.An.!:;!i"l..r.„.v.rt..bra..(p.r«,y,.-..fW <-- -.-; ...f, luHraUr...... 
 
 I- Mil. 
 
 mill hiniUr vicwk 
 
 III mill 
 
 :,, Ki^Mir:::;':; ......yp.. ..r .,/..-........ r... v...« » 
 
 :,5. ,..f;:!.n: ,;.:;. n«.i,.H ..r p.ir.:.y,». .,( Kdmon,o...u,..; r,.,r vi.w «..kMI> 
 
 from without , i- , 
 
 m Ski of S...phl»..iurina.; .S«.,/...«o«.un.,, rorv-A..« -. :...'l ""-'"' 
 
 :.7 
 
 <M) 
 
 e,i 
 M 
 
 Ml 
 70 
 71 
 72 
 
 73 
 
 (MIHrilH 
 
I 
 
 The Madrosaur Edmontosauius from the Uppe: 
 Cretaceous of Alberta. 
 
 ro 
 
 71 
 72 
 
 73 
 
 INTHODK TIOX. 
 
 Till' Hiulri Miiiriilu'' tire ii Kconp of )ii>rl>iv(ir<iiiH iliiinhtinrx <>f whirli 
 most of the gfiicra mi' from the cotitiiH'iit <;f North AiiH'ricH. Thi' lilinittirr 
 rclntivo to this fiimily is loth vnhimiiioiiw ami iiivoivcfl. Tin- isiiiiir 
 (iosrri|)tioiiN won- l)aM'(i oftci on iiiadctiut:' matcriui wliicli iiavc litllf 
 information as to tlic relations of tlic fo; r .-prrn'iiti'ii aiui tli«'ir varirty 
 wliich lias provi'ii to lie much (irratcr 'i h. <nn at first supiioscii. Tin- 
 rupiiiity of the evolutionary chain*" ^ ''X'k plnce in tilc^e reptiles 
 
 itiiriiiK Cretaceous timi s, especiaiiy toward tiie close of the period, resniliiiK 
 in H wondi-rfid diversity of form, could not, in the circumstances, iie fully 
 appreciated. At tiu- <'arly stage of neologicai and paiu'ontolojtical investi- 
 (catioM the iiorizons supplying dinosaiiriun remains iiad l)een otdy liroadly 
 determined, (ieoiogical e.xpiorution was at that time carried on, in tiie 
 west particularly, under trying and arduous conditions; trans|M»rtation 
 WHS liiflic'uit; and i jugii-und-ready metiiods of collecting were used l>y 
 parties most ina<le(|uately equipped for field worlc accoriiing to picMiit 
 day stan<inrds. It is not surprising, therefore, in spite of the l>rilluinc\ 
 of the pioneer few who undertoolc ])alu'ontologi('al investigation, imd tlie 
 ardour which they lirouglit to hear on their worit an<i l>y whicii tliey w re 
 upheld, that errors were not avoiileii. It does not detrai't from the I'xcei- 
 lence of their results to now find that diversity of form was not alway- 
 recognized, that, for instance, generic terms were employed to include 
 ty|M's iKd only widelv sej)arat( '' liy time intervals l)Ut also liy very di'i'itled 
 differences in struct 
 
 Recent discov. during the lust six years in the Helly I{iver and 
 
 Edmonton f.irmatii on Red Deer river, Alherta, of nearly complete 
 slteietons ol .-iveral distinct types of hadrosaurs liave provided excellent 
 muterii.i ft" smdy and description, thrown nuicli light on tlie osteology 
 of the groi'n and ofM-ncd tlie way for a eiiissificution of its memhers. 
 
 In the ilidwing pages a description of the large iiadrosaur Kdmonlo- 
 ^(•ii-UHregnbs, Lamhe- from the Kdmonton formation of Red Deer river, 
 /iliiertu, is followed by a projiosed division of the Ha<lrosaurida' into 
 three subfamilies the classification being iiased principally on tyjie and 
 other material resulting from the exploratory worlc of vertebrate pala-- 
 ontological field parties of the (Jeological Survey, Canada, in Alberta, 
 largely supplemented by tlie discoveries of the American Museum of 
 Natural History, Ne" York, in the same regifin and to the south of the 
 International Bound; ry. 
 
 Of the two skeletons on which the genus Kilmontomurun was estai)- 
 iished in 1917, one is unique in that the majority of the bones of the hea<l 
 and of the remainder of the skeleton were found together naturally dis- 
 
 'The uuite Hwirosaurid* pmpmed by Cope in 1S60 I'lS'l) titu pren«<tetice over Triv ndontiilie uMd by 
 LydekLer in Vmi ud later liy Marsh in IbWI. 
 
 •A new KBnufc and aoeritw of oreMtleM h*ilros'»ur from the KdiuDnton forinution of Albert 'tt:iwa NuturaliRt . 
 vol XXI, No. • f)ct. 1017, pp 115-73, pl«. II and III. 
 
articulated, well picscivcd with iciuaikal)ly little ilistoitioii, in a soft 
 clayey sandsloiie easily removed a!id leaving the surface of the l»one« 
 clean. This particular state of preservation provided an opportunity 
 for study and description seldom accordeil. A j)res(!rvation of this nature 
 was especially welcome in the skull as in the nenerality of cases the elements 
 of the skull in dinosaius are foimd in place and are not easily freed from 
 each other. Any jiarticular hone is larfiely hidden hy the suinjunding 
 ones, and it is a matter of difficulty, often of im])ossil)ility, to remove it 
 in order to see it in all its aspects. Also, when a skull is jjreserved with 
 the elements in i)lace any distortion that may have occurred is likely to 
 atfecl all of the elements to a greater or less e.\tent. In a naturally <lis- 
 articulati'd skidl, disloi'tion when present in any parlictdar hone is confined 
 to the limits of that hone. With few exceptions :dl the drawings repro- 
 duced in this memoii' in illustration of the te.\t were ma<le liy .Mr. Arthur 
 Miles under the supervision of the writer. 
 
 MATERIAL OX WHICH Kl)Mt)XTOSAriUS IS BASKI). 
 
 Edniontosdiiriix is represented in the cfillections of tlu' (ieological 
 Survey hy remains, including the skull, of at least two individuals, as 
 follows: 
 
 Collection of I0I2, lldmonton formation, Ued Deer river, Ali)erta, 
 field No. 27, Cat. Xo. 2288, t;inotype, from opposite the mouth of Three 
 Hills creek, at 21)0 feet ahove ilie level of the river: the skull figured and 
 descrihed in this pajM-r, with most of the vertehra' in place hack to tin- 
 sixth catnlal, one hind limh lacking a few jjlialanges, one humerus, hoth 
 puhie hones together, one ischiinn, the greater ])art of the right ilium, 
 and some rihs. Estimated length of individual considerahly over .'}() feet. 
 From field measurements the length of tht^ following hones are: femur 
 47 inches, humerus 27 inches, ischium .54 inches. The discoverj' of this 
 si)ecinu'n was made hv 1-. Sternherg, assistant on the (Jeologieal Survev 
 party of 1!U2. 
 
 Collection of I!)l(», Etimonton formation. Red Deer river, field Xo. (*, 
 Cat. Xo. 2280, paratype, found hy (i. V. Sternherg 7 miles west and north 
 of Morrin. in sec. U>, tp. 31, range 21, on the west side? of th(> river, 90 feet 
 ahove water level: a skeleton lacking some of the hones of the feet, the 
 tail vertel)ru' hehind the fifth caudal, the premaxillaries and the predentary. 
 There is a possihility of the right ilium not heing pr( -eat. The hones 
 of this individual are splendidly preserved and lay closely scattered within 
 a grey, clayey sandstone which is easily removed leaving the surfaces in 
 good condition. The elements composing the top of the skull are pre- 
 served together. The remauiing hones of the head, including the mandi- 
 hles, were found disarticulated. Femur 49 inches long, humerus 27^ 
 inches, left ulna 30 inches, left radius 20 iiu-hes, largest right rih 50 inches 
 along the curve, dentary 30 inches, depth of dentary in advance of hase 
 of coronoid pr'^fcss, from the lower surface to external alveolar horder 
 ti\ inches. 
 
 Of the type skeleton the skull anly (Figures 3 and 4) has as yet been 
 prepared. This work was skilfully performed hy L. and C. M. Sternherg. 
 
/ 
 
 
 
 •9/ ^|H 
 
 um^^^JmrnmSBSmi 
 
 "1 f -J^ 
 
 
 1 
 
 Hi w^ 
 
 
 ^I^Kf :- '' ^^^ti^ 
 
 m^ 
 
 1^'^ '*'^|mHI 
 
 Ip^BJi '•" -'"^K? 
 
 i- ' . J"'- 
 
 
 '>'^3^H^P^VI 
 
 
 Br iTb •S^Snk^ 
 
 ■!#'f^# 
 
 ^B £v '"Vx^i^^d 
 
 *' ? ^^•-, 
 
 ^^^1 
 
 H •w^' -^ss^E^k^^^^^^Bi 
 
 ^ JMil^l 
 
 Iftv ^ '•4iiOHH9 
 
 ^t-^if'^l 
 
 
 V -^^JH 
 
 ^^^ '.^^" Sr^^BH^BLiJM 
 
 
 ff^^K v' s£nRjk'^£|^^^H|^B^H 
 
 n 
 
 
 K'^H 
 
 
 kJH 
 
 » JBi'Ai ""'■' V 
 
 
 1 \|'s , ' 
 
 
 i li^^^. ' 
 
 
 rV wH 
 
 1 IBr y^-v^TilKPl 
 
 — 5 
 
 ? 2'i3 
 
 S s-S 
 
 
 *2S 
 
 79:3 
 
 " > * 
 J? 
 
The elements of the skull of the paratype, and the few vertebra; and 
 bones of the fore limb mentioned in this rejwrt, were prepared by G. F. 
 Sternberg who had cliarRe of the 1916 expedition. It is h()|)e<l soon to 
 assemble the elements of this skull and to so mount them that as many 
 as possible will be removable for study purposes. 
 
 As the greater part of the skeleton is present in the above specimens 
 an open mount of both is contetnplated. 
 
 OSTEOLOGY OF EI)MOXTOS.\URUS. 
 
 :5 
 
 I 
 
 SKULL. 
 
 The skull of Edmontonaurtis is large, massive, and long, high behin<l 
 a!id low in front. Posteriorly it is higher than broad, anteriorly it is 
 greatly expanded horizontally outward into a beak-like termination. 
 
 Viewed from the side its outline is subtriangular, high behind, approxi- 
 mately straight horizontally below, flat above behind the orbits, with a 
 long faeial slope descending rapidly forward. 
 
 As sedn from above the skull is broadest in its posterior half-length, 
 much expanded in front, and greatly constricted behind this cxiKinsion. 
 The outline of the occiput is squarely transverse, and the margin of the 
 snout has a semicircular curve. Behind the concavity of the anteri()r 
 constriction the lateral outline is broadlj' convex backward. 
 
 The posterior height of the skull is greater than half its length. The 
 maximum breadth behind exceeds the full lateral expansion of the Ix'ak, 
 but is considerably less than the half-length. The orbit is large, as is 
 also the narial opening. The supratemporal fossje are of fair size, but 
 the lateral temporal ones though high are greatly rediicecl in width. 
 Concomitant with the po.sterior height of the skull is a long (|Uadratc. 
 The great development of the flattened snout is remarkable, and the dcj)th 
 and robustness of the mandible are equally striking. 
 
 Elements of the Skull Known in E<hiionto-iauru<. 
 
 .\lis|)honoid 
 .Vngular 
 
 .Articular (in part) 
 Ba.-*i-o(>cipital 
 Basisphpiioid 
 Dentarj- 
 
 Ert()ptpr\'Koi(l (Trans- 
 palatine) 
 F^xoccipital 
 Front al 
 .Tugal 
 Lac'hrvTnal 
 Maxillary 
 Nasal 
 Opisthotic 
 Orbitosphenoid 
 Palatine 
 
 Ms. 
 
 Pariisphi'iioiil 
 
 I'd."!!. 
 
 An. 
 
 I'arictal 
 
 r. 
 
 Ar. 
 
 I'ost frontal 
 
 I'of. 
 
 i %'. 
 
 I'riMlcntary 
 
 I'd. 
 
 bs. 
 
 I'rcfrontal 
 
 I'rf. 
 
 Dn. 
 
 Pmnaxillar}- 
 
 Vmi. 
 
 EpI. 
 
 Prcsphcnoid 
 
 r.'>p. 
 
 Exo. 
 
 Proiitir 
 
 I'rol. 
 
 F. 
 
 Pterygoid 
 
 I't. 
 
 J. 
 
 Quadrate 
 
 Q- 
 
 L. 
 
 Quadrato-jugal 
 
 Qj- 
 
 .\fi. 
 
 Splenial 
 
 •S',,. 
 
 .V. 
 
 Squamosal 
 
 .s,. 
 
 Opot. 
 
 Supra-oeeipital 
 
 Snr. 
 
 Or.ip. 
 
 Sur.inKular 
 
 .S'fl. 
 
 Pal. 
 
 Vomer (in part) 
 
 |-. 
 
■s-s&s 
 
i 
 
8 
 
 (ramum. Tho .•raiuutii propt-r or hruin-caNO o( Edmonlomurus 
 thouKh small in pn.portif.n to tho sizo of tlio head was strongly put toaether 
 I he honcH (.nt.Tii.K into its formation won- thick and hetwoen many of 
 them coossifieation tt.ok place; at l.-ast in the paratvpc. on which the present 
 description is principally base' the brain-case, ulthouRh excellentlv 
 preserved with wonderful detail of structure and form, exhibits few of 
 the sutures externally in the side walls and basicranial axis. In the brain- 
 cavity none of the sutun-s have been detected. 
 
 In E<h>,ontomiiriis, and apparently in the Hadrosatiridw irencrallv 
 ossification took place IhrouRhout the cranium, in fact th<! bniin-case iri 
 tlie Hadro-siuirida" appears to have been as complete as in the Ceratopsida" 
 and m both group.s an early dosing of Jie sutures marked a departure 
 from conditions in the typical reptilian skull in which the cranial elements 
 tend to remain distinct throughout life. 
 
 In the paratype of Edmontomurust, in the external surface of the 
 sidewalls of the cranium, the suture between the alisphenoid and the 
 prootic IS preserved above the foramen ovale. In a large surface extending 
 lorward fr()m the alisphenoid, representing the orbitosphenoid and the 
 presphenmd no sutures are seen marking the separation of these bones 
 trom each other, a though their upper boundaries are very distinctiv and 
 clearly dehned, and in the case of the orbitosphenoid and the presplienoid 
 their lower limits al.so. 
 
 Inferiorly the suture between the basi-occipital and the basisphenoid 
 is visible on either side, but not near the midline, and it can In' traced 
 iipward (jii the side walls for a short distance before trace of it is lost 
 ALSO ill the occipital condyle the division between the basi-occipital and 
 the exoccipital is dear and distinct not only beneath but externallv and 
 posteriorly as well. 
 
 An early and perfect union of the opisthotic with the e.xoccipital, and 
 ot ttie epiotic with the supraocdpital would be expected, but in the side 
 walls l)ehind the foramen ovale no sutures can be detected suggesting a 
 division between any of the periotic bones. Nor is there a suggestion of 
 the extent of the supraocdpital bone. 
 
 The cranial foramina are well preserved and, relying on them, with, 
 the aid of the few sutures that are visible, the proportionate size and relation 
 to each other of the elements entering into the formation of the brain-case 
 are tairly well established. 
 
 MeasunmvnU of SkuH iif Ti/pe of Edmnntosmirux. 
 
 I-i'iigth of .sku 
 
 11 1 i.-urod in a .straight line from tlip pi>st('ri<)r .'(iKe .,( -hi cxocciuitil 
 prowssjparoccipital) to the centre of the anterior preniaxillarv i.n rein 
 Horizontal length from anterior premaxillary margin to a point" verli.'allv below 
 tno preoeci])ital edge 
 
 "'"'^of dent' r"-^''' "^ Posterior end of nasal at the midline of wkuil to lower silrfaei- 
 "'^'^orbital'ri''' ""''""'■*''^ ^"'^'"tically d(,wn from eentre of frontal contribution to 
 
 Width of orbit at midiieight 
 
 Length of supratemporal fossa 
 
 Alaximum width of same near its anterior end 
 
 Width of infratemporal fossa toward its lower eiiij 
 
 Length of quadrate 
 
 Breadth (antero-posterior) of external face of same at niidheight 
 
 Mm. 
 
 1114 
 
 KHit) 
 
 .541 
 
 20,5 
 
 \m 
 
 15.1 
 
 8.5 
 
 60 
 
 420 
 
 7« 
 
Mm. 
 
 1114 
 
 KHit) 
 
 541 
 
 205 
 
 \m 
 I5;i 
 
 85 
 60 
 
 420 
 78 
 
 ?'*'"!*,'• Cranium of Edmontosaurus, Cat. No. 2289; i natural size; inferior aspect. Alt, 
 wuphenoid; B», basisphenoid; Boc, basi-occipital; bap, process of basisphenoid; Ezo, eioccipital: 
 r, frontal; >, surface for jugal; L, lachrymal; /. car. in, lower entrance of internal carotid arterj-; 
 mx, surface for maxillary; N, nasal; occ, occipital condyle; Opot, opisthotic (paroccipital process): 
 CArsp, nrhitosphenoid; P, parietal; Pasp, panwphnnnid; pmx, surfarc for upper Iiii..> .of prcmaxillarj; 
 Pof, poatfrontal; Prf, prefrontal; Prot, prodtic; Pap, presphenoid; pi, surface for pterygoid; v. 
 surface for quadrate; Sq, squamosal; age, squamosal cotylus; Soc, supra^occipital ; «(/, supra- 
 temporal fenestra. 
 
10 
 
 l)i.-.l«n.T in i.^traiKl.t lii,.. fmin tl... m.tr.. itnullii.r „f .kull, of i|„. ,,r..ii,axill,.rv 
 
 lH,r.l,.r anl.rinrly t., thr imnWrmr ni.l of tl... uim-r prnnaxillar lii'.l, " {w. 
 
 Miixmiiim hriailiii iktmss il,,. j)rriiiaxillari.Win fn.nl (.viiiiim.,|, *Am 
 
 ll.'iKht i.f upper (Mil ol rorcnoMi pr(«'.«» alxjv.. I.,w.r surfacf .,f .l.-niary . . 28h 
 
 lla.i-occi,,U„l ilioc.) Figurfx J, (?, «„,/ ,'(7. This is a n.l.ust, .•..nipa.f 
 hone as l.n.a.l as lon^ but with a .•oiiiparativolv slight .Icnth \s tl„. 
 |)..st,.,i.,i- incml,,.,- of tlic> Lasicraiiial axis it is in ronlacf su|)cn.-|,.,s("..ii„rlv 
 ui h the .•x(,c(ipilals. and anteriorly with the l.asis,,hcn(.i.i. Su|)..|o- 
 antcnorly its .o.mk arics aro not soon hut it conios in contact h-rc with 
 ho prootic an<l no il()ul)t also to soino extent with tho onisth'>tie. It enters 
 larK.'ly into the formation of the ocdpital eon.lvlo. hounds the foramen 
 inaKnum holow-. and in advaneo of this .)iM"ninK its upper surface forms .-. 
 lartjo ix.rtion of tho floor of tho brain-cavity beneath the medulla oblonuata 
 It supplies about five-sevenths of the articular surf: co of th.' occinitai 
 condyle, the exoccipitals between them provi.linjr the roinaimnK tw..- 
 sevonths. Its contribution to tho condyle includes more than one-half 
 of its l(.wer surface. ViewiiiK tho Imno from Ix-low. it is narrowest in 
 advance of the condyle, broadoniiiR a^ain to its contact with tho basi- 
 sphonoid where ,ts breadth equals that of tho -,on.dvlar r)art. In front of 
 the broad convexity of the condyle tho lower siirfafV of tho bone is trans- 
 versely concave, and on oitlwr side antoriorlv a rugose l„it not paiti.ulariv 
 prominent tubercle is .loveloped whose rouRhnoss and fumiditv is con- 
 tinued on to the basisphenoid. Tho contact of the basi-occipital and the 
 basisphenoid ,.s seen in the paratype toward either side of the lower surface 
 and can be trace.l upward externally for a short .listance. IN.sterlorlv 
 the basi-occipital extends back for some distance bevoiid a point verticallv 
 ix'low the roof of tho foramen magnum. 
 
 Mivsiirimritlx i>J ISiisi^Hxii>itnl t.f E<hmiili)!i'iiiriis. Siiiriiiun Cut. \,,, /.'s7*. 
 
 Hivadth iiifi.rii.rly in posliTiur half faiToss condvli'i ' "!,,, 
 
 Hrcailth inlrrinrly at jiinclion witli l)asi>phcii.,i,l. about . |(V> 
 
 l.cnijih, iiilcriorly, about .^'^ 
 
 Thirkncss Hlrjilh) at (■•■iilrc of basisphcnoi,! colitlibution to' (Mvipitai n.n.lvl,- 
 
 . 'ilwii't ' ■ ■ .,,, 
 
 rhickiic.-s (ili'plh) at niiiilinc in front, alx)ut ■;,•, 
 
 Ex(HTi,,iua (K.ro.) and OpiMhntic (Opot.). Fiqiiirs .7, (/, 7. „„,l >i; 
 lhe(.xor<;pitals, the lateral eh'tnents of the occipital seKineiil of Uu- 
 cramiim form the side walls of the brain-cavitv in its most posterior p;irl 
 IxMind the foramen magnum on either si(h-. and contribute jargrlv to the 
 occipital condyle. They are clo.soly united, without trace of stlture to 
 the opisthotics with which bones thev evidentlv effected an earlv and 
 thorough fusion. In their ctmipletion -f tho occipital condvle exteriio- 
 posterKjt-ly they project freely backward and are convex in'feriorlv and 
 external y; they are angulatod behind, and shaHowlv concave inte'rnallv 
 whore they form upward and backward extensions' of the floor of th'e 
 foramen magnum. 
 
 In the occiput the exoccipitals aro thought to have been separated 
 partly, if not wholly, by the supraoccipital, but in tho ab.s(.nce of sutures 
 defining tho limits of tho latter bone nothinc definite can bo -uid in this 
 
I 
 
 II 
 
 28H 
 
 ■ III. 
 
 IIIO 
 
 1g 
 
12 
 
 tonnixion. In CamplonauruK t\w siiprn-Kocipitnl boiin.lrd the fornnii'n 
 mngnum alM>ve and in Kdmonlottaunm it in probable that it iMTunifd the 
 xami'jwsition. 
 
 The opiflthotic iwrtJon of the PxoiTipiul-opiuthotio romplrx rxtcnds 
 backward, with a xliKht inclination upward from the horizontal, and 
 (levclopH posteriorly a larRc forwardly hooked paroccipital procii-rt directed 
 outward and downward beneath the squamosal procesH which it supports 
 and resembles somewhat in general "^hap*-, and beyond which its iH.inted 
 end projects. 
 
 Above the Inti'ral convexity of the occipital condvle is n c-on«>ave 
 surface in which are four foramina (FiRurea 26 and 27, /A', A', A7, jug. v, 
 a. c. /., A//) to be referred to later, piercing the exoccipital. A strong, 
 backwardly directed ridge, springing from the basi^ccipital, bounds the 
 convexity above and merges farther back into the lower marginal curve 
 of the paroccipital process. Above the ridge the external surface is widely 
 channelled longitudinally l>ehind the fenestra ovalis (Figure 20, fen. ov ), 
 and It is in this upper depression that the division between the 'oJsthotic 
 and the epiotic would be expected. In this channel was probably lodged 
 the !.tnpes whose anterior end closed the fenestra ovalis. 
 
 Supra-occipital (Soc). Figuren, 4, 5, and 6. Extending back from the 
 transversely angulated upper rim of the foramen magnum i.«s an extensive 
 flat surface of bone which lies between the paroccipital rocesses of the ex- 
 octipital and broadens backward with an inclination upward from the 
 horizontal. No indications of sutures are foun<l in this region i nd evidently 
 the 8upra-f)ccipital which would be expected here in the mid'ine. and the 
 exoccipitals have completely coossified. It is impossible, t.ierefore, to 
 determine definitely the limits of the supra-occipital, but it is thought 
 probable that the greater part if not all of this surface is supplied by the 
 supra-occipital and that this bone entered into the formation of the 
 foramen magnum above, confining the exoccipitals to the flanks of the 
 opening somewhat as in Diclonins mirabilia as figured by Cope (1883, 
 
 A definite ridge extends backward from the foramen magnum along 
 the midline of this supposed supra-occipital surface, and anteriorly on 
 either side of the ridge the bone is widely excavated upward behind the 
 foramen magnum, the exoccipitals flanking the excavations externally. 
 
 The back border of this surface is straight transversely for some 
 distance outward from the midline and then suddenly acquires a greater 
 backward protrusion which curves evenly outward into the paroccipital 
 process. On the upper face of the protruded border on each .side are 
 curved impressed lines (I .gure 8, c) which may indicate the postero- 
 external limit of the supra-occipital. 
 
 The anterior contact of the supra-occipital with the parietal is not 
 seen, but posteriorly there is a space between these two bones, a low space 
 which extends outward for a short distance, about 20 mm., from the 
 midline beneath the squamosals. 
 
 Viewing the skull from below, its extension backward from the foramen 
 magnum is conspicuous. A noteworthy feature, in a posterior aspect, is 
 the lowness of the parieto-squamosal arch in comparison with its breadth, 
 as well as the smallness of the parietal contribution to the arch. Beneath 
 this arch, following its curve, and closely .applied to ir, except near the 
 
i:{ 
 
 niidliiic, i.-« tlic MUprn-ocripitD-pitniciiiiitMl tinli. Mtlwiiii tlit- piirii'liil uml 
 inniT purt of the ■< lUaiiio^iiU and tia' liiiulir iMinh'r <if ihi' ^iipraHxcipital. 
 th<' Hpnci', n'prt'scniiiiu apparently a <iiiitlninrc of the |Mi->lti'in|Miral 
 fiiH'striu (iccanioMcil liy the viry liriiitcil entry of the parietal into the 
 occiput, cxtcnils forwar<l for at ha-'t .'»0 iniii., iM'Vond whii h it lia* not In en 
 possilili! to follow it. I»«r iiK from either side of the sp; . e is a well-delilied 
 Kroovu (Finure (I, tl\ in the s(|ii:iniosal which ascends outward to the n|)per 
 -urfare of the hone and there disappears. Ketweeti the sipiatnosal and 
 •he supra-occipital, and lielow t!ie icroove is what appears to lie a foraniinal 
 ,/eninK iKit(un> tj. <■). 
 
 liumxiiheiioitl {/is.i. fiiimi.s ,,tl, T.nmlJi!. This element, preceding 
 tiie hasi-i" I ipital ill the hasicranial axis, and conxtitutinn the inferior 
 niemlier of thi' parii tal seRnieiit of the cranium, in a robust ixiiie of dis- 
 tinctive shiipc. It is in contact 1>< hind with the hasi-occipital, aliove 
 with the alisphenuids and <irl)itospheiioids, and presumahly siipero-po?,- 
 teriorly with the prootics aUo, hut exce|)t in front where ii runs heiienth 
 the orhitosphciioids its upper houiid;iries catitiot he made out in the material 
 availalile. .Anteriorly it extends forward, withoi'* trace of suture, as the 
 parasphenoid. 
 
 In inferior .ispeet this hone is hroad iK)stenoriy, contracts forward, 
 and then throws otT to either side, from slightly in advance of wii.it is 
 considerei. to he its midlennth, u stout process which is directtd oulward 
 and slightly downward to connect with the uppor border of thi' pterygoid 
 lietween that hone's alar extensions. In front of tht> processes the hone 
 narrows rapidly to the iireadth of the slender paras|)henoid 'I'lie outline 
 of the hone, as seen from i)e' )w, m.ay lie said to he irregularly star-shai)ed 
 with five ruys composed of tiie anterior constriction, the lateral pterygoid 
 processes, and the po.stero-lat< ral angh'S, the rays repre.sent«'d hy the 
 processes being longer than the others. 
 
 The lower surface of tin' basisphenoid is crossed at about its midlength 
 liy a strong transverse ridge connecting tlie two i»roccsses infero-posteriorly. 
 Hehind this ridge the lower surface of the bone lies in the general 'plane 
 of the iiasi-occipital, is transversely concave, and postero-luterally is 
 rugosely tumid next to and supplementing the basi-oecipital tubercles. 
 The |)osterior slope of the transverse ridge faces backward and very slightly 
 downward. In advance of the ridge the surface of the bone between 
 the proces.ses is widely concave in all directions, and is inclined strongly 
 upward so as to face obliquely forward and downward, much as in I'."in- 
 odon. ^Iedially on the ridge a small, tongue-shaped process is developed 
 which points downward with a slight backward curve. 
 
 The pterygoid processes are flattened above and below, are thickest 
 behind, and narrow to the front, the cross-section at the base beingtriangular 
 with the !'-pex of the triangle directed forward, and the sides lengthened. 
 They terminate bluntly. Covering their thick, obtuse ends and extending 
 inward with decreasing breadth for a distance of over 60 mm., on their 
 front faces is a rougheneil surface denoting contact with the pterygoid. 
 Between this articular surface and the narasphenoid the bone comes to a 
 sharp edge. 
 
 Supero-laterally, above its contraction behind the processes for the 
 pterygoid, it sends outward a thin, triangular, wedge-shaped flange, set 
 at an angle to the horizontal so that its upper face is inclined forward. 
 
 MM-J 
 
14 
 
I.'. 
 
 r)ii» tiiiiiKi- KpiiiiKx fruin ii ntuiit l>arM' ixtiiKlinit from the ptiryKoid prorivMt-H 
 to l'4|i»w thr ronilllfn uvulr. Tin- oiitlinr of the liiiw of t|ii> tiiitiKr ifi 
 li'iitit'uliir III (■roMM-Mi-ctioii. with the IniKth of tin- liii!' iinirly itpial to tivt- 
 tiriM'!* itft liri'itdth. 
 
 FliMi'd well forward iM-iicutli tin- Wum- of tin- ftaiiKf if* llu" rxli-riial 
 o|Mniim of a loiiit. j-traiuht panxanf, dinrtcd upward, forward. aiMl inwanl, 
 and •■ntcriiiK tin- pituitary >*pa<<' from ImIow, for tin' traiiMiiix.Hioii of the 
 iiitirnal <arotid artery. Aliovf tin- flaimr, alxnit midway Ixtwccn tlir 
 
 aiitirior end of its haxc and tin niiiiini txil for tin' third and fourth 
 
 iicrvi'!', U a foraimn for a liran«li of thf carotid artt-ry o|N'nin|[ dirrrtly 
 into thf main ;>a><saKi'. Tliiw upper o|M-ninK is Kinall aiid oeeiirx within a 
 coiifuvity of eoiisideralile size (about l."» mm. in diameter) in tJie external 
 
 rturfiice of the I Skirting thi- ha^«e of the tIaiiKe infero-|>onteriorly if 
 
 a we||-«h'fined (inMive for the eourw of the artery to it)* entry iM-neath the 
 Hanne. 
 
 The iipiM-r Hiirfaee of the liajti.xphenoid ixmteriorly forms the anterior 
 |)ortion of the Hoor of th<' medulhi ohlonnata. It is here |M'rforated hy 
 the forwardly chreeted paxHnnes of thi- sixth nerves whieh enter tlii' infundi- 
 )>uhnn. one on either side of the midline, from hehind. Kxtemlinit down 
 into the (treat thickness of the iHWie, in eontinimtioii of the infundiltulum. 
 is the space for the pituitary hody ahoiit in line with the hinder shipe of 
 the tran.^verse ridjte eonneetiiiK the pterygoid processes inferiorly. 
 
 MiiiKiiriiiii Ills III HiiKi/'iihi mini iif Eilniiiiiliisiiiiriin. .S'/Hiinirri Ciil Sn ','Sli 
 
 .Mill 
 
 Iiiicro-piistiTJcii lirc.i^lili I III 
 
 liifcriiir liriaihli ImIijiuI iiti':yK>>ii| |ir<K-i'».si>M (i;( 
 
 Hri'ioltli ii.riiK" iiicrvKiiiil priH'i'H.xcN Iisd 
 
 hifirii-iiiiti iiiir liri'itdili jO 
 
 'riiirkiii-!>s iili|iilip nt iiiiillirii'. ht'twi-cn iiriuin iif sixth mrvi's hihI jiiriilnliliuliiiii. 
 
 til liittcr surfiiri' lirliiiiil IraiL-vcr-i' riiluc liti 
 Tliickni'ss iili'pilii friiiii Iuwit <ni| of piliiiiurj- space to lower siirfarc iH-hiiul iriiiis- 
 
 VlTsl' riilllr ;j- 
 
 .•^iiprriiir lircailtli liclnw i- itic fontnicii IH 
 
 I'<inisi,h)noiil [I'liy.). Fifiiirr-s .7, .:. 7. niitl JH. In Kflnioiil<Mfinix 
 this memhnine Ixine • lieneath the presphenoid as a forward extension 
 from the iiasisp'ieiKiiii with whicji it was evidently coalesced. It is 
 slender, higher than tiroad ixisterioily. and is sj)out-shap<'d in advance 
 iif the line of the olfactory nerve exit. I.eadinjr iiack from the spout, 
 towaril the liasispheiioid, is a passajie alioiit IK mm. high and S mm. 
 wide, mostly thioiitih the paraspheiKiid Imt within the presphenoid to 
 aliout one-tliinl of its hci(jht. Whether this p.-issajje reaches the liasi- 
 spheiioid has not lieeii ascertaineil. The suliile lietweeii the par.isphelioid 
 and the presphenoid i- indicated externallv on l.oth sides l.v a line of 
 deniaicatidii running foiward lielow the level of. and nearly parallel with, 
 the Hoor of the olfactory lohcs. 
 
 Misphinnid (Ah.). Fifiiirci .',. :,. 7. S.niul 2H. The alisphenoid is. 
 Ill Its characteristic position in the reptilian skull, in ailvaiice of the iiruotic, 
 Ixiiiiidiii): the large foramen for the trineminal nerve in front. It forms 
 the sidewail of the hrain-cavity above the hinder portion of the basi- 
 phenoid. It connects postero-superiorly with the parietal, siiperiorlv 
 with the frontal, and pxtcrno-.superiorlv with the ivwtfroiita! Inferiorlv. 
 
'1 
 
 i 
 
 16 
 
 that openinK The pancto-alisphcnoid Miturc runs fc.rwnnl fr-.n. , 
 
 In advanco of and above the foramen ovale a stnnt ri.lm. ; -i.„„i 
 winch running upward an.l outward forms an infed a S luj TS'"; 
 (.one between the supratemporal fossa and the . rb 1 1 Uv U T i 1 
 -n Its upper part constitutes a buttress which eacheV^he n^st r nt^M ^ 
 
 Tl,n ^ III' ^"'"""'l' "^'••'l'' <'«^PJy notches the hinder bonh-r of the alisnhen.,!, 
 The outer openrng of this foramen is contracted in front nfr'„.-? 
 narrow gn.ove extends forward on the extermil s r "c of \'hf lln^l 7. r' . 
 a.-n,modat.on of the ophthalmic bran..h ol le hVtrner 4" tL 
 
 (.f '• 7VX,,L -'4 fomtho ''r'r^ 'f ^T""* '?' '^ fragmentary craniui 
 
 .';;::."■'" -f i:;: tsbid ^r-^^ ^iz^^-z ?- s 
 
 the alisphenoid, to X frontal H?vhf' T '*''?>""' -"^ L^^ ^""'•''^« "' 
 t .s probable that ,n E^montosaurus also the course ifthe boundary of 
 
17 
 
 thr alisphrnoid lay from this particular nerve opcninn up in front of its 
 angulated huttnw. The area in udvanee of the alisphenoid, regarded as 
 the orbitosphenoid, eonnerts superiorly with the frontal and inferiorly 
 with the basisphenoid. The jiresphenoid in front forms the floor beneath 
 the olfactory lobes and may include that part of the area from tiie opening 
 for the optic nerve to that for the first or olfactorv nerves, and upward to 
 the frontal, but the proportionate extent of the contact of the presphenoid 
 and orbitosphenoid with the frontal is not known. Apparently the inferior 
 connexion of the presphenoid with the basisphenoid and parasphenoid is 
 extensive, limiting that of the orbitosphenoid with the basisphenoid. The 
 presphenoid in its extension upward to the frontal flanks the olfactorv 
 IoIm's and the orifice for the exit of the olfactory nerves on either side, 
 but whether it or the frontal encloses tiie opening above has not been 
 ascertained. 
 
 Proiitic (ProL). Figures 4, 5, 8, and 26. This cranial element is behind 
 the alisphenoid and in front of the epiotic and opisthotic, neither of which 
 latter, however, are distinguishable as distinct bones in the Ednwnlo.saunis 
 skull, both, following the usual rule of cranial development in reptiles, 
 haymg probably early fused, the epiotic with the supra-occipital and the 
 opisthotic with the exoccipital. Superiorly this bone reaches the parietal, 
 and inferiorly the basi-occipital, and possibly al.so the basisphenoid to a 
 limited extent. 
 
 The proiitic is pierced by the foramen for the seventh or facial nerve 
 (Vll). In front it completes the opening for the trigeminal nerve behind, 
 and Its hinder border is deeply notched bv the fenestra ovalis (?+ tiie 
 fenestra rotunda). 
 
 In Edmontosaurus (specimen, Cat. No. 2289) the suture between thi? 
 proiitic and the alisphenoid is shown in its upper course. It is seen to 
 leave the foramen ovale high up in the posterior margin of the opening 
 and to ascend, first for a short distance slightlv forwanl, and then for a 
 greater distance backward, to the parietal above. It is clear, therefore 
 from the position of the suture, that the greater part of the opening 
 IS m the alisphenoid as it is in the alligator. In the Jurassic herbivore 
 Camptosaurus (Gilmore, 1909, p. 210, fig. 5) the foramen ovale is mostly 
 in the nrof)tic, as it is also apparently in Tricerutops. Hay in his paper 
 of 1909 on the skull and brain of Triceratops remarked that"in Triccmtop^ 
 the suture between the proiitic and the alisphenoid may be provisionallv 
 drawn through the front of the foramen" (foramen ovale). 
 
 Superiorly the prootic extends outward from the parietal as part 
 of the floor of the supratemporal fossa. At the outer edge of the floor 
 It IS angulated horizontally and overhangs the lower portion of the bone 
 which IS concave externally in a vertical direction down to the biisisplunoid. 
 llus upper angulation or ridge, originating from the proiitic, extends 
 horizontally backward, parallel to a similar ridge developed in the opistho- 
 tic, and merges posteriorly in the upper face of the paroccipital proce-<s 
 of tlie exoccipital. Between the two ridges the external surface is vert ii'aliy 
 concave and in this concavity the suture marking the antem-^uperior 
 boundary of the opisthotic is to be looked for leading upward !ind ba.kward 
 , "V i ?''**I.'"''' ovalis. This suture is shown in this position in a crMiiium 
 V* {'■flcnorfon" sp. figured by Osborn in 1912 (p. 18, fig. V.\. Anier. Mii< 
 
 -No. l2i). 
 
■'■^mA 
 
 18 
 
 V_ 1 i / 
 
 Opot 
 
 KJKurc 8. Cranium of Edinontosaurus, (at. No •>'>89- 1 
 natural xue; superior aspwit. Ah, alisphcnoid ; P, frontal L 
 ;','.'i','?l'"'?iv^' T^^-PP?^- opisthotic; f . parietal: /'„/, p;,si: 
 frontal: /V/, prefrontal; /'ro^ pro6tic; Soc, supra-orcipital- .S,; 
 
19 
 
 Parietal (P.). Figun'.s 3. 4. .',, i;. S. and Jf!. This 1) >nr, the coalesi't'd 
 parietal pair, forms tlio roof of the brain-case from ImIuikI the (•♦•rcbrum 
 to the (crcbcllum, and, in the upper surface of tlie skull, passes backward 
 from the frontals to the s<n.amosals, separating the supratemporal fossa-. 
 The parietal is longer than broad, narrow for a consi(h'rable distance in 
 front of and Iwhind its midlen>jth, and ex|)anded outwar<ily al>out e(iiia!ly 
 at either end. Medially it rises l>etween the supratemporal fossa-, with an 
 increasing amount of lateral compression, to the plane of the upper surface 
 of the skull as a high interfossate ridne cxtrenx ly narrow above. Its 
 lateral faces within the fossa- are concave from belo.v upward. 
 
 Supero-anteriorly tlie i)ariet;d m( cts the frontals to the full extent 
 of their combined posterior breadth in a zitrzat'P'd. transverse- sutun. 
 .\ntero-externally it is in contact with the p(!stfiontals in a short suture 
 which, leaving the upper surface of the skull, passes down the front mariiin 
 of the suimitemporal fossa and runs forward for a short distance on the 
 lower ')order of the same. Figure ."). /'. Posteriorly it meets the s(|uam(;sal> 
 frcm below in a curved transverse suture about half-w.ay up the postericr 
 face of the supratemporal fossa. In continuation of its median ridge it 
 passes back narrowly, to the occiput separating the s(|uamosals. The 
 upper surface of this interstiuamosal portion lies in the general plane of 
 upp<-r surfa( ■){ the skull and is longitudinally channelh-d. 
 
 The parietal connects inferiorly with the alisijhenoid in front, with 
 the prootic farther bock, and with the exoccipital behind. The sutural 
 line marking the contact of tla- lower border of the pari(-tal with the ex- 
 occipital and i)ro(itic runs forward horizontally in the- Hoor of the supra- 
 temporal fossa. Its anterior continuation "as th(- pari<-to-alisphenoid 
 sutun- ris(-s with an outward curve and terminates at tin- pejstfrontal a 
 short distance in advance- of tlu- anti-rior margin of the supratemporal 
 fossa, see Figure o, P — .4/.s-. 
 
 Th(- parietal posteriorly in its outward curve within the supratemporal 
 fossa, at a l(W(-r l(-vel than the stpuunosal, enters largely into the formation 
 of the posterior face of the opening. Inferiorly it as.sists the exoccipital. 
 prootic. and alisphcnoid in providing a partial Hoor to tin- opening. With 
 a small externai -m itribution from the postfrontal it bounds the opening 
 in front. 
 
 A narrow, distinctly marked groove, cominuo -s along the summit of 
 the interfo.ssate ridge, apparently marks th(- original division of the parietal 
 pair. 
 
 M<<isiiriiiiint.'< I.. I'l 
 
 Iff S/H film II. fill. \ii. ,'*S!t. 
 
 bcTiKtli ;iliiiiK llic niidlinc above 
 
 MaxiiiuiiM aiilirior t)rra<ltl) within the siiiiialiiiil>:iral f(i 
 
 -Maxiinmii ixfrtcrior lyroailth . ; 
 
 Hi'i({lit at iiiidlciijith 
 
 Brrailtli at liiiillciinth 
 
 Mm. 
 I US 
 l.-)0 
 I4S 
 
 Squamosal {Sq.). Figurea d. 4. ■',. 6. 7. and S. This bone is 
 and with its fellow forms almost the whole of the hinder part of t la- 
 surface of the skull. It bounds the supratemporal fo.ssa post(-i 
 enters largely into the formation of the external border of the- samt 
 IS in contact with the parietal, postfrontal. (iuadrat(-. exoccipittil 
 'supra-occipital. It is broadest behind, an<l niediallv in front exien 
 
 large 
 upper 
 riorly. 
 '. and 
 , and 
 sivt-lv 
 
20 
 
 Ssrsii K;'„:-,E Sr.;ti:,;-i-;.'-a ■,■,•• 
 
 to th.' under sX;„rwhVui^.Z,l''' u' ^A""*'"" " ' "" P"'**^''""*' 
 thickens outwardly toTho cot •.; S t oua U'e" Tt'lxJri"" ^''^^ ''" 
 
 s,u,,mo.„] for ..™o ,|i,X „u,.Tr r from X-TS'I ^''t" °' "" 
 
21 
 
 .Mm. 
 19.-) 
 
 22r) 
 SO 
 50 
 3»> 
 11 
 
 parietal, extprno-postf'riorly thi- postfrontal, ami aiitoridrlv the iia.sil ami 
 prefrontal. Postero-externaily it reaches tiie anterior "niarKin of tin- 
 .suprateinporal fossa at about the latter's nii(ll)rea(itli. Kxtcrnally toward 
 the front it extends outward hetwei-n the postfrontal and prefrontal, and 
 eontributes narrowly to the formation of the orbital rim. The prefront.-tl 
 and nasal together form an angular emarKiiiation of the front border, the 
 extent of contact with the nasal l)einK about one-third of that with the 
 prefrontal. As vieweil from below the frontal meets the prefrontal to the 
 full extent of the latter's breadth which is ecpial to about three-fifths of the 
 l)readth of the frontal, the line of suture l)et\veeii the two running trans- 
 versely inward from the orbital rim with a strongly zigzagged course. 
 Between this contact and the longitudinal midline <(f the skull the frontal 
 extends forward thinly beneath the nasal to a point nearly as far advanced 
 i'.s the supero-anterior edge of the prefrontal, the full fronto-iiasal lapping 
 length bemg about 111 mm. Beneath the nasals the frontals meet along 
 the midline except for a short distance in front. 
 
 Postfrontal. (Pof.) Figures 3, J,, 5, 6, 7, S, nnd 2(1. The postfrontal 
 i.s a conspicuous bone of considerable size and i.s remarkable in that it 
 develops a large fold or pocket subsidiary to the orbital cavity. Seen 
 from above its outline is irri'gularly triangular with the apex of th«- triangle 
 directed outward, the long ba.se being gri-ater than either of the other two 
 sides. In lateral aspect its outline may al.so be said to be roughly triangular 
 with the apex downward. 
 
 For one-half its length internally it is in onntact with the frontal in 
 a zigzagged suture extending from the centre i )er curve of the 
 
 orbital rim to the centre of the anterior margin oi me .- - ratemporal fossa. 
 The posterior half of its length internally forms the ou. t half of the an- 
 terior margin of the .supratemporal fossa and contributes largely to the 
 formation of the outer margin of that opening. Overlapping the squamosal 
 t() near the posterior end of the supratemporal fossa it constitutes with 
 that bone the supratemporal arcade separating the supratemporal from 
 the infratemporal fossa. 
 
 Curving outward and downward and narrowing as it descends the 
 postfrontal is gibbous externally to a marked degree and encloses within 
 it.self a large pocket which is a backward extension of the orbit and lies 
 extermr to the postfrontal contribution to th(! postorbital bar. This 
 pocket, opening directly forward, relegates the upper part of the post- 
 orbital bar to a position within the orbit, well removed from the exterior 
 surface of the skull. The presence of this pocket occasions modifications 
 of shape ill the postfrontal bone, not previously described, so far as the 
 writer is aware, !•• any known member of the Hadrosaurida>. 
 
 The excavation of the postfrontal bone to form the postorbital pocket 
 is exten.sive, measuring fully 115 mm. in fore-and-aft depth, anil leaves the 
 I'livcloping walls thin, particularly on the inner side, where over a con- 
 siderable area the bony tissue is only about 1 mm. thick. In the t xtcrnal wall 
 a thickness of from about 4 to 7 or more mm. is attained. In the sweeping 
 inward curve infero-postcriorly the thickness averages about 5 mm. The 
 excavation in its backward extension even enters for a short distance 
 that part of the bone which overlaps the squamosal. Both in the roof 
 and floor of the pocket the bone becomes thicker, especially so in the 
 loMiier on approaching the frontal suture; in the latter the tliickening 
 
Prr 
 
 22 
 
 fossa, o v, ,; 'u,^ L /'f r""r"''"""'"r^" "f »'"■ "-"Prat...,. 
 
 fossa in its u-|)(T half i«..<nsiii( width of th.- infratcinp, 
 
 m. t' '•' '" '""•'* ''"' '"••h'-yn.al an.l in s„ ,1„ 
 
 , "^ ^»P'-'-''-"nt...i.,r portion of the orb, 
 
 • im. It IS houndci hchmd bv the frontal, on 
 
 .nn,.r s,,!,. ..xtonsi v.-ly l.y th,- nasal, in front Z 
 
 n-x>.x\ and bclmv anteriorly for a short distance 
 
 . laehrymal. It projects baekward into i 
 
 Jroital bone. narrowniK about equally from b. 
 
 s . > to a point behind. Th<> prefronto-fron 
 
 Ml are IS sinuous and both bon.-s are here strc 
 
 and thiek In front the pr..frontal overlap.s < 
 
 K.l„mn,o,aurul.ar.Xo.'"'l.,'9''f «'n^iclerubl,. extent, and deseendinR also ov 
 ! natural mz,.; inferior view 'aps the hu'hrymal. The anterior end i« nomt. 
 
 '^lA^^t^Zi. Siiilnx^' r' '-'^--' " the oiS"*^ 
 
 I'rS, pnfrontai. outline is broadly sinuous. In annroaehinLr t 
 
 With ..nly « »lwl5 ,r„Si," ^T,;™S,^^^^^^^^^^^ '»■«■."' 
 
 a .leeplv' onSv^> surface ?lcntH''^ l^^i'-^n.nXy the prefrontal presort 
 between the Iach™i i^front and thn^ .""fZ^"'}- ''"'' »^"''k«ar< 
 
 bounded by the lach™ymi?for iK .nfl" /T/"*' 'u''^'"''- Internally it i 
 of the len^h b tt^ n.^^Vn'^f^ont"^ 
 '■ontact of the latter, howeyer, bdngtt great" ^'' """"' P'-"P°«'""-'' th 
 
23 
 
 uiv'iinj front 
 The inner 
 
 rior curve (if 
 I'wiiat to the 
 from a jxiint 
 ipiatiniporal 
 "It distance 
 •■ liostfronta! 
 external to, 
 i"* in contact 
 H' formation 
 ' postfronfal 
 ifratemporal 
 
 ' piefnmtal 
 or lialf than 
 I' witli the 
 l(io\vn\var(l 
 in so doing 
 the orbital 
 ntal, on the 
 front by the 
 <listance by 
 id into the 
 from both 
 >nto-frontal 
 here strong 
 verlaps the 
 i<! nasal to 
 also over- 
 i« pointed, 
 orbit the 
 laching the 
 ipidly out- 
 ■ the orbit, 
 bone thin 
 •avation is 
 lit 22 mm. 
 titly back- 
 illy above 
 1 and the 
 '•«■>< of the 
 
 over that 
 t overlaps 
 il presents 
 Jaekward, 
 lally it is 
 •emainder 
 tions, the 
 
 lini.r 
 
 1 iKiiic 10. HiKlit liK hryiiiiil (jf Kdim 
 
 A, external if i» ■- . . . ^ 
 
 /'r/, prcfroiit 
 
 10. HiKlit liK hryiiiiil (jf VA iiliiwiurus, ( at. No. i;>Hi(- ■ natuml »i 
 
 aspect; H, internal iispcct; C, posterior a»p<Mt; /,, laclirvtiial; .V. nas 
 tal; ;, surface for contact with jugal; pmi, witli preiiia.xiriar.v. 
 
 sise. 
 nasal ; 
 
 Lacbnjmid (L.). Fiijiiris J, .{, .7. ,v. .'y, w. niiil II. This bone is over 
 twice as lonjj as high, and somewhat wedge-shaped, being thickest behind 
 and thin toward the front. It is in contact with the nasal, prefrontal, 
 jugal, maxillary, and premaxillary. When in position in the skull its 
 length is in the directum of that of the lower premaxillary limb. 
 
 Viewing the lachrymal in jxisition from without it "presents a surface 
 with an irregularly four-sided outline broadest behind and pointed in 
 front. Sujiero-anteriorly it is largely hi.lden beneath the termination of 
 the premaxillary limb. It is oveiiai)|)ed su])ero-p(,steri(.rlv bv the pre- 
 frontal for a considerable distance. Inferioily it unites for the whole of 
 its length with the jugal. The posterior border comes to a sharp edge 
 which is decnh'dly protrudent outward in its upper part. This border is 
 free and forms that portion of the orbital rim between the prefrontal and 
 the jugal where it projects l)ackw;ird into the orbit to a considerable 
 <'Xtent. The lachrymal ('(mtributi'in to the orbital rim is mostly below 
 the midheight of the orbit. Postero-inferiorly. at the liack end" of the 
 jugal contact, it extends a stout, jxiinted pnicess downward behind the 
 jugal. The external surface is somewhat convex in a direction at right 
 angh's to its length. 
 
 In the disarticulated skull. Cat. Xo. 2289, this bone is still hrmlv 
 attached to the na.sal and prefrontal, but the jugal, maxillarv. and lower 
 immaxillary hmb are separate from it .so that its true shape'and the full 
 extent of the majority of its surfaces are revealed. The bone ends abruptly 
 in front with little decrease; in depth forward. Outwardlv the surfac'e 
 covered by the premaxillary limb supero-anteriorly is large, "equal in area 
 to about ono-haif of the entire external surface. The outer overlap of the 
 prefrontal above is small, as is also that of the jugal below. 
 
 „T^1 '""*''■ surface of the lachrymal, revea' d in the disarticulated 
 skull, is interesting. Toward it.s posterior end the bone is greatlv thickened 
 
mmmmm 
 
 mmmmm 
 
 Measurement. „f Hig,, L,„„nj,„nl „f S^rUan, r,„. X„. ,>s.'> i,l,.„r,icutate^ ,kul,). 
 
 I'xtornal Ictiftth. in ii struiRht line •^'"' 
 
 Kxlri'iru" ^.. 
 
 Kxlrcmc I'xtcrnal dcplh 
 J'osicridi- (.pciiiiiK of la<hrviii:i 
 
 _\irticiil iliaiMi'tiT .," . 
 
 Traiisvcrw ili;im(>icr 
 
 180 
 
 SO 
 
 l(» 
 
 2:i 
 
 ..M.;^;;^;:„K;J"^,j;^/^''-n.™nurus. r.,. So 2289; internal as».,.t. 
 'The Ottawa \atiir:.!ist, vol. XXVll, 1914. 
 
25 
 
 'cull). 
 Mm. 
 180 
 80 
 
 40 
 23 
 
 it is n'ltitivcly hrmul. PdstwMriy it is in rontart with tin- frontal which 
 it tivcrhips to sonn' extent. In its narrow jM>stcrior part it hounds the 
 prefrontal inwardly, then suddenly expandiuK it extends downward in 
 front of the prefrontal to the lachrymal and the ixwtcrior end of the lower 
 premaxillary limb. Itscont.n t with the lachrymal is short hut it meets the 
 prernaxillarj- limb for a distance slightly over one-third of the hitter's 
 length. MecominK slender anain it passes forward above the narial openinjf 
 to meet the upper premaxillary limb and continuinK forward exterior to 
 that i)rocess it ends thinly with a rounded outline just beyond the anterior 
 <nd of the ofM-ning. Alonjj the letiKfh of its contact with" the pieniaxillarv 
 limb th- nasal thins jjradually to the front in the same ratio that th"e 
 premaxillary limb narrows to its posterior termination, thus providing 
 a uniform transverse breadth to the premaxillo-nasal portion of the roof 
 of the narial opening. Hehind the termination of the upper i)rem,txillary 
 hmb the lower bonh-r of the nasal becomes dccid> llv protnident. llifly 
 arched at ' ^t and then desceiidinfr backward, as the h^ne rapidiv expand-^ 
 to the lower pn-maxillary limb. Retired inward from the lower end of 
 this prufrudent bor.ler a spur of bone is sent forward bv the ii;isal within 
 the upper edge of the premaxillary limb, and in contact with the nifixilhiry, 
 increasinn the extent of the naso-})remaxillary contact and completing the 
 enclosure of the posterior end of the narial openinR within the na.-^al bone 
 as seen in lateral aspect. 
 
 Pnnmxillanj. {I'mx.). Fiyurcs 3 and .',. This bone consists of an 
 anterior portion expanding horizontally outward, a long, backwardiv 
 directed, gradually narrowing lower limb, and a relatively >hort upp("r 
 limb also directed backward. As viewiul externallv it is in contact with 
 the nasal, the lachrymal, and the maxillary. The two |)rcinaxillaries 
 together give an anterior breadth to the snout apparently little less than 
 the maximum breadth of the skull behind. The lower jimb bounds the 
 narial opening inferiorly for three-fourths of the hitter's length, and con- 
 tinuing beycmd the posterior end of the opening, overlapping both the 
 nasal and the lachrymal, it terminates some distance short of the pre- 
 frontal. The upper limb passing back with increasing tenuitv i>ii the 
 inner side of the nasal assists it in the formation of the supranarial b:.r to 
 a point at about the midlenpth of the opening. The anterior end of the 
 nanal opening is within the premaxillary. As seen from aix.ve the front 
 margin of the premaxillary curves outward and backward for ai)out one- 
 fourth of the bone's total length; the outline is then inward and backward 
 concavely in participation of the transverse compression of the skull at 
 and above the maxilla. The front border of the anterior expansion of the 
 premaxillary is recurved for some distance .so as to roof over an extensive 
 cavity which opens backward. The bone throughout is thin so that 
 what outwardly might appear to be a heavy ending to the snout is in 
 reality greatly lightened. The floor of the cavity is smooth and is con- 
 tinued backward as an extensive, more or less depre.ssed tract which is 
 subdivided into three principal areas two of which together oceupv the 
 t)readth of the bone at the mouth of the cavitv and lead from it, and the 
 third is situated beneath the narial opening. The inner anterior area is 
 the most sunken of 'he three, is the least extensive, and is separated from 
 the other two by ^ flange of bone which passes downward and slightlv 
 lurward from the base of the upper limb in continuation of the upper 
 
IM^. a.l. .MTupi.-s tl... nitir.. l.r..u,ltl, „f th.- U,mr lin.l,, and " t n "a ,. f 
 «nt..n.,rl,v, has an outli,.,. that. takn. i.. .onj.m.S ;rt , ' t o ' 
 
 nferryl to a« on-urnnR at th. p,.Ht..ri.,r ..„.! ..f ,h,. narial ...".ni 
 
 ,<»"' 
 
 ';", .surfu.o for .-.•..,p|..ryK„i,|; >, fnr uS f, ^mW n""!.: .»«,'. anlrrmr ,naxillur,v pro..-,, 
 prrmasiUary;,,?, f„rptrry»'i,i. "'""'"^ iiiaiillar> prm-f--: ;,„,j., ^„rf,„.,. f,,^ j^^.^^^^ jj^^^Y „ 
 
I'upyiiiK till' 
 the riii.HC I 
 f «o Munkni 
 iniirkcd ofT 
 ■ amiiiint nf 
 loiijftT tlmn 
 kI« at I'itluT 
 
 ■ll in <lt'(|M»t 
 
 thut of thf 
 
 ■rior (Iciiiar- 
 
 i>al already 
 
 niiig. 
 
 t is slinhtly 
 
 rounlily till- 
 
 tln'!(trai(ilit 
 
 l» 
 
 B 
 
 view front 
 ury pr(i(i'».H; 
 latini': pmn. 
 vL'i linili II 
 
 27 
 
 alvii)lar Ix.nl.r, in iimkIi lon^.r tlmn ll.i. >li>|iitiK si.l.s. whirh .|,.mc.-im| 
 .•..nniy.ly fr..n. a l.nm.llv .urv..! aiMX. It i. lat.iallv lo.npr.,..-.! and 
 tint. alH.ve. and thick aloiiK it. I.m.r I.UKtli. Tlir inner fa.-,, is n.. „ wh..le 
 rather flat in great contrast t.. the varied r.-li.f uf the ..iiter <,ne Fxier- 
 nally the hone is m..M prot indent, and thickest, at alwHit inidhiiKth at 
 a .listai.ce above the alveolar border e.pml to about one-sixth of its niaxinillin 
 heiKht. iron, here extends upward the nmose surface of atta.h.nent nf 
 he front en, -.f th,' jugal t,„. Ix.ne thinniiiK rapi,llv iipwanl. IVom iIm- 
 lower. overlunKinK cIkc of th,- surfa,,- for th,- juk,,! a n.l.ust rhl^e runs 
 horizontally l.ackwar.l with .liniinishinK str,-n(tth to n,ar th,- ,-n.l of the 
 Ix.n.-. I h.- surface b.-twe.-n th<- ri-lg,- an.l th,- alv,-o|ar bor.hr is v,-rti,-allv 
 .-on.-av,-. In a,lvan,-.. of th,- surfa,-,- for the juRal th.- .-xt.-rnal fa,.- is 
 tumi,l upwar.1 from th.- alv.-.,lar l,or.h-r until on apiinmchiiiK th.- ant.-ro- 
 suiM-ri..r b..r,h-r it b,..-o,n.-s v.-rli.-ally .-oncax in a niaiKinal .h-pr.-ss,-,l 
 ar.a in which lay th.- as.-.i.dinn low.r limb .,f th.- pr,-maxillarv 'ri.is 
 ar.-a gams ,„ wi, th an.l in th.- amount of its .-on.avitv as it pro,-.-,-.|s 
 f..rward .-ausijiK th.- ant.-rior <-n,l of th.- bom- to b.- thin-.-;iK,.,| in front and 
 sharply amtulate.l .suiH-r.M-xt.-rnally. Aiu.th.r ...n.-av.- ar.-a. still mor.- 
 pronoun.-.-,! in its ,h-pr,-ssion. o,-.urs in th.- p..st.-rior half of th,- bon,- 
 b.-tw.-.-n th.- sh,.|l- ike upp.-r surfa.-.- of th,- r.d(£. an.l th,- p,.st.ro-sup,-rior 
 b..r.l.T. I nhke th,- ant.-ri,.r .-on.av.- ar.-a this post,rior ..n,- is wi,|,.st 
 n.-x to th,- surfa.-,. for th.- atta.-hm.-nt ,.f th,. jugal an.l ,liininish,.s ,a..i,llv 
 
 ba.-kwar. 1,-avinK the hin,l,.r ,-n,l of th,- 1 ,- thi.-k an.l n.bust. The 
 
 bo...- IS f un in Ih.- api.-al r,-Ki,ui. pn-s.-nts a flatly ,-onv,x surfa, ulwar.l 
 
 an,l IS shari,-..,lK,.,l above. .Anteriorly this api.-al surfa.-e .l,.s,.,.n,|s int.; 
 
 Shi.) ill, II y 
 fyfi>/itiry,/iii,/ 
 
 imi.i J 
 
 < u 'v;"-.^. I'"' ''■" ■"'l*il''"V- l'''l^"i"". P-Tym,„l. an,| i..r..„„.r. u„„l „f .■,|„,„„,„..,„n,- 
 
 m.'.'viii""'''"?'"'."'""''' "'•"■«'""' <l«1>i«'ssion for the r,-.-.-pti.,n of the p.,- 
 cncv-.'.r. !."'.' •"r"''""'.^-.i',i^ separat,.,! fr.m. the pos„.n.-sup..'ior 
 s .;.; .^ 1. '■ 'x "■''''!■ \''""--'"'> ''"■•'■'•ti''l K'„ov.. which .-mai-Kinates th,- 
 .M ,,r bor,l,.r b.h.n.l th.- .-.p.-x. Th,- nnt,-ro-sup,.,ior portii.n of th,- 
 
 iC'v't r." '" 'i'""' '■'""'"'* '"'"' ""• '""'•'• -'"-f^"-'' "f t'"' l.'iH.rvn.al. 
 iviow the laelii-ymal contact ih,- suilac for ili,. atta.-hment ,.f the jukhI 
 
28 
 
 rm-wM ilownwnnl. JKHoming ••..nmvf ami nion- riiRo^r in itn l,,w<r 
 with a Mu.l(li.n iii,r.-»M.. in th.- tlii<kn."M« „f tl„. |,..ii.-. Th.- Hurfu... f,, 
 jiiKHl IS roiinhly Mitii.inular in (.utlin*' with th.- rurv. furwiml 
 
 II..' antrr.H..HU[MTior iM.r.l.T of th.> niaxillarv ix (rah.v.r.sHv na 
 
 HI..! IS furniMl.fd with a smooth, shallow uroovr in whi.h lav th.- in 
 
 |K>st<rior proc'ss „f tin- nasal .lir.'ctc.l forwani hclow th.. hin.l.-r .'ii 
 
 th.- nasal ..iMning. In <-oniiniiation forwani ..f this hor.l.T is a lat.- 
 
 .•on.|.r..ss...l |.ro.;..ss (ant.-rior maxillary pro.-.ssi whi.-h .'xt.-n.ls .-onsi.!. r 
 
 ..•yon.1 the mam l.nvr t.-rmination of th.' hon.' an<l is s.'parat.'.l fr„ 
 
 .y a .l.'.p .■mHrKination (ant.'ri..r maxillary i.oi.h). Th.' ,M,st..ro-su|.. 
 
 bonl.'r of th.' maxilla is als., narrow an.l s.ippli.s a v.rv niuos.' s, t 
 
 surfa.,' for th.' atta.- mu-nt of th.' low.'r ..lu.. .,f thP palalin.' In .nnt 
 
 tion m.'kwanl of this hor.l.r o.'.urs a ,)ost.rior pr...-.'ss iM'tw.'.'i. w 
 
 an.l th.' h.avy, r.>iin.l.'.l .n.l of th.' I>..ii<' is a iMist.ri.ir n..l.'h .,f Mn 
 
 pr..l..,rl.ons than th.' ant.ri.,r ..n.'. Th.- post.ro-maxillarv pr...'.ss r.-.'. 
 
 u'l.1'2 .'! "";■■■.".•■'">■ tl..'.|.t.ry«oi,l as th.' latl-r pass.-s forwar.l In 
 
 withm th.' palatin.' It is Kr.M.v.'.i l,,.l„w for th.' upp.r l..,r.l.r of 
 
 .•.'t.)pt.'ryK.,i.l in s.i.h a nianiu'r that its t.rinination li.'s .■\f..rnal t.. 
 
 '•" ,"' ^''pt'TytJoi.l. Th.' p„st.'ri..r not.h is hl|,..| l,v th.' thi.'k. 
 
 I"''","" "f " <«"Pt.'ryKoi,l. Th.' p..st.ro-.'xt.rnal Mirfa..' l,.'|..w 
 
 n..t.'h IS niKos.', nirv.'s .'..nv.'xly .lown t,. th,. l.-v.'l .,f th.' alv.'olar Ix.i 
 an.l r..,',',v,.s in .'|.,>,. .-..nta.'t th.' .•.•t.,pt..ryK..i,l an.l (..'low it th.' pf.'rvi! 
 h.' Mtt.T IxinK ov.-rlapp.".! I.y th.- form.r. Th.' post.ri.,r .'.'.I of 
 maxillary ri.lK.' is l.oun.l.'.l ahov an.l h.'hin.l l,v a ^roov into wl 
 . xptlr'si.'r''" '"" "" "■ *''"*"f'"'^>«"''' *^»"'"' it l..'Kins its rapi.l p.,st. 
 
 «itl,)l""""f'' ""' '"?;■■■ ^■'"'•' "(*'"■ •"••'•'''""'•y is fiat as a wh.,1.' in .'..mpari 
 \Mtl. th.' oul.T ..nc. th.' api.al r.-^ion is .l.'.i.l.'.llv hollow.'.l out. an.l tl 
 s a ^hal^.w .'oncavity of tlu- surfa.'.' .'xt.'n.linK fn.m th.' ant.rior .n.l 1, 
 past mi.ii.'njjth. A .'..nspicumis fcattiri' ..f this face is a flativ ar.li 
 r..\v ol Muall, .'ircilar foraminal .ip.'ninRs .'xt.'n.linjr Im'Iow th.' ini.lh.-i 
 of th.' t,„h. inn. Miints al.,,v.' th.' first an.l laM t.'.th. Tli.rc i« 
 l^oram.'i, to .'a.'h v.Tti.'al s.'ri.'s .,f t.'.'th. H.'tw.'.'n th.'s,. .Irntal foram 
 an.l h,. alv.'oh.r l.or.l.r is a w.'ll-.l.'fin,.,l vas.-uh.r k,,„,v.' of th.' s;, 
 hn^th an.l with n.arly th.' sam.- .'urv as tl..' foiaminal r..w. In tl.o lo' 
 ^Zlrj '"V"';'' '■•""•'ivity ar.« two foramina, one lar^.', th.' ot 
 sn.all. pla.'.'.l .los.- toptht'r an.l IcadinR .lownwar.l. 
 
 liuT.' a.v hfty-on.' to Hfty-thr.-.' vertical scrii's of maxillarv tc, 
 ...•.'.ipyinu s..v.'n-.',Khths of th.' total length ..f tl..' l.on.', th.' .lental mauaz 
 t.'rm.natinK closer to the posterior than to tl..' ant.'ri..r .'n.l. Tl..' cx^.t 
 an.l int.'rnal alveolar borders are at the sam.- l.'vel 
 
 tl.o . i.VV''""/'-^*!''" '"'■'^r ^'""'""'na o'-^-'"- tjci.eath the pn.trud.'nt has,' 
 the surface for the attachm.'nt ..f the juRal, an.l one, ev.'n larRer, is pr.s, 
 ...nsiderably in adyanc.. of the same surface near the superior bord 
 •Wo ':"°^ «•''":'•»' ••';K>"» «'•'• "thrr small openings disposed as shown 
 XI r •'-^l''' rt^feience is mad.- to the maxillary teeth und.r anotl 
 lieaumK (paRC o5). 
 
 M,<,.'<tinm.„h nf Ufl MnxUlnri, of h:,li„„„l„s„i,r„.^. C„l. \„. JJSH. 
 
 Maxinmm l.'iiuih. iitiout . ^^ 
 
 LptiRlh at Icvcf of .■ilv(^)l,ir ImjoIits .....' ■; 
 
'.» lower pirt 
 irfiirc for tlii' 
 >l. 
 
 rwly niirrow 
 y Ihi' infero- 
 inilcr end of 
 is II latiTiilly 
 foiif^idf ralily 
 iifi'd from it 
 lfro-su(Kricir 
 iKosi' suliiral 
 In t'lintiiiiia- 
 Iwecn which 
 
 h of Mln:ill(T 
 iri'ss nM'fivf.H 
 witrd to lap 
 irdir of the 
 'rnal to and 
 <• thickciicil 
 ' below llie 
 eolar l)nrder 
 '■ I>>«'ryisoi(l, 
 end of the 
 into whieh 
 )id posterinr 
 
 eoin pari son 
 t, and there 
 or end liaek 
 itly areliiiijf 
 ' niidlieiKlit 
 lerc is <irie 
 al foramina 
 f tlie same 
 11 tiie lower 
 , the other 
 
 illnry teetli 
 il magazine 
 he external 
 
 i'nt base of 
 •, is present 
 ior border. 
 s shown ill 
 ler another 
 
 Mm. 
 122 
 
 Mi'liclil ul ii.iilli'iiKth 
 
 l.<'liKtl> of <li'iitlil liiiiKiKitir ' ,'^* 
 
 Hri!i.llh lercw* nlvtiiliir iH.nlir-. iit iiihllitiKth ",'1 
 
 Hr'it'lili at l.m..r i-lKe of ..irfii.r l„r :iii,„ t.tnrnt of' i.iijal :„ 
 
 •,.xm.un. „r,..M„..n ,.f ,..,1. (,..|„«. ,.,,,..,1,., ,,,„,..'r * ,„i,|i,.„„,h ,.f ,,.-,..„l „.,.«..- 
 
 Xi 
 
 J'iml. (J.). Fiyure^ 3, 4, ami /.;. Thi^ element is lonir. fliiii and 
 
 |. a.e-hke, with an ol.tusely ai.Kulated lower outline, and p h den t 
 
 dM.ve fornnnK the lower boundaries of the orbital an.l infrate, ,!, 
 
 Mniiurv Its extreme HiKth to its maximum .lepth is in mI.o,, th 
 IHopor „m of to .-. 1, eonneets antero-superiorlv with th laehrvnl 
 
 iti ,1 o ./,.';', M*'' "'"' ^"'"/"'^'V ••""H'l'Tably behind its n enuth 
 
 «ith II.. po,tfrontal by m.^ans of its asrendiuK process |„|,ind il rbit 
 
 lA.ernally .t nite.jeeN „ forwardly diree,..,! angulation of ,|,' fn.n. l-'nier 
 
 '// 
 
 
 <'at. 
 
 KiKure M. I,oft jugal o( K<lmont.)sauru.,, , ai > 
 »ifo. /, surface of contact with laclirjnial; mi with 
 w.tl. quadrute; „. with ..ua.lratojuKal; ;„,/, «'ih pl,8t 
 
 No. 2289; intcriiul aspi'ct; ! natural 
 inaxillHry; iml, willi puLitinc; .;, 
 
 postfrontal. 
 
 iikrv'ln VlfJr" """I "^ ^he lachrymal and the highe.st point of the max- 
 llar> to the lower edge of the premaxillarv limb The anterior end of 
 
 .\f^^*i ®""'^'-*' •'' J'ontact. Antero-superiorly it is grooved in a lonKitutlind 
 Imction, more deeply near the orbit than toward the front to rn'ov 
 
 \l TA • ''o""'^'hat similarly curved, downwardly and foAvardlv 
 
 -lireeteti lower ends of the orbit and inf^ate^poral fossa.^ The ascending 
 
39 
 
 
I 
 
 <«■ 2289; J 
 of contact 
 
 •"<•'/ i 
 
 /^ 
 
 d 
 
 Be. A, external view 
 outlines of transverse 
 )r quadmto-juKal: ;i(. 
 eceived in squamoeal 
 
 31 
 
 process contributing to the formation of the postorhital l.ar, is particularlv 
 loiiK and sicndor and pass.-s up on the inner sitle of. and in a long contact 
 WMth, the short descendMiK pn.cess of the postfrontal and the front border 
 of the inner wall of the postfrontal pocket. Posteriorly the jUKal exten- 
 sive y covers the (piadrato-jURal and abuts against the outer front In.rder 
 of the quadrate for some distance above the (luadrato-jugal. 
 
 Qnwirato-jagal [Qj.) Figun's 3, .',, ami lo. This l,„ne is a thin 
 s.il.tnanKular plat.', slightly higher than long, highest anteriorly and 
 longest near the bas... Its front bord.T is straight, the loxver one ,„,,r|y 
 so hut undulating, and the posterior on., curye.l foiward alx.ve. It thins 
 to t he front border which is approximately verli.'al when the bone is i„ 
 position. Mor.' than on.-half of the extern.-d surface is coyrre,] by the 
 jugal in a close, rather smooth contact lacking the numerous incnialities 
 of the junction of the jugal with th.' maxillary. Posteriorly the .lua.lrato- 
 jugal narrowly overlaps th<- tpiadrate whose antero-ext.Tnal bonier is 
 cniarginat.'d to receive if. A groov<- is .hyrlopcd i„ th. horder behind 
 h<- apex into which the front border of the .,uadrat.- .-dM.y.. its emaigination 
 tits. 
 
 Qu'Klmle. (Q.). Fiijurv^ ,i. ,;, ,nul 1>!. This bone ...msists of ■, 
 tiMMsv,Ts..ly compress,.,! l,:,r from whose iniu.r surface a larg... thin HaiM'e 
 IS directed mwanl and forward. It conii,.,-ts with the cpiadrat., -jugal and 
 jugal ant(.ro-ext..rnally. with the pterygoid internally by means of th.' 
 liange, with the .squamosal superiorly, and with tli(. sura'ngular and articular 
 inferiorly. It occupies an almost vertical p sition in the skull with the 
 liead immovably htted into tlie pit in th.. .,iuam..sal. an.l with th.. low.-r 
 end 111 th.' man.libular c.)tylus. 
 
 Vi..w...l fr<|m with.,utit is narrow.-st al.ov... and b..nt slightly f..rwanl 
 
 fnm. .1 h..r end s., as to hav.. an ..v<.nly ..oncav.. post.rior ...itlin.'.. H..|„w 
 
 h.. mi<ll..ngth the anterior b.,r.l..r is broa.lly but shalL.wlv ..marginat...l 
 
 for the r......pti.m of the narrowly ..yerla|)ping p.,st..ri.,r curv.. .,f th.. ,,„a,l- 
 
 rat.)-jugal. I he anteri..r b.u<l..r starting from the hea.l, with th.> latt.r's 
 tiansv..r.M. thickn..ss. lK.com..s thin in its .l..s....nt t.. th.. .|ua.lrato-iugal 
 
 ouTlap when, it thickens t.. son,., extent, but is again thin for a sh.,rt 
 
 I esent'' '''T.'/ "' "^^'''■/'"'l f »'"' »"""■- I" i''^ "PI"''' P."t th.. .pia.bat.. 
 
 r s. Its a tla(t..n...l surfa.-." facing oufwar.l but with a slight obli,,uity 
 muai.l an.l backwanl, an.l the p..st.'ri..r bor.l.'r is .,btus..|y angulat.-.i 
 Appn.a.-hing n.i.llength the external surfac... with an incivasing obli.,uity' 
 
 wists iinyard so as to form a face .hrecte.l n..arly ba..kw..,r.l an.l ..„:•; 
 mw.u.llymanarn)wl).,rder which is the .lownwanl cntinuation of the 
 upper p.,sterior angulati.m. At the low(.r en.l the posterior surfa..." is 
 again angulated. ' '" 
 
 The inwardly and f..rwardly direct<>d flang.- of the (,uadrat.. is giv..., 
 
 I, Lrrr !u ',"'"''■ '"'""•'■'' !'^ *'"' ™'"" P'""*'""- ^^^ '>"^'- t'^tentls the wl.ol.. 
 ngth ,,f the b.,ne and is situafe.l, in the lower half, ab.,ut mi.lwav betw...... 
 
 aik horder. 1 he flange is thin, triangular in lateral ..utline, an.l n.a..li.>s 
 Its greatest protrusion in line with the centn- of the quadrato-jugal c.ntact 
 
 M29-31 
 
32 
 
 tiul It 1 .>,.s rapidly witli a coneiivoly .•urvcd .,Ik,. to its ,,„v « or , 
 rml-Hk!" f'Vr'"^' '"*'7 "™^'>' ^♦'^''^''t •"'«•• to til"! a,l ' Tl n S 
 
 an.! i!s'in;rTirm.li,Iil"'l''""'?'V '^^'- '^^ ^'"'''^'^t '"""'^^^^ tran^v. 
 .iiKi nih int.) lie maiuiiliular cotylu.s joint v I'oiitrihutcd to In- tho <, 
 
 |v..rd and bacU.n-d, and fits a^ain.t the artic-ulai he S. ' f" 
 
 King the qua* rate's contribution to the inandihu ar hiniio Tl ■ i , 
 
 attieular extension of the lower en.l acts as a pedestal for'ti.e ^^^l.Z 
 
 A roughened surface on the inner front of the Ijonc extendiiiLr for 
 
 of the short stout process or spur descending from the s(,u ims, 
 advance of the pit in that element into which U.e "ead of tlli "imdla 
 
 Above the narrow, curved surface which marks the overl-m of tl 
 
 ^,r i"" V"^.^'' ? ^r''"^' '■«"«^''>' ^t"'^**^^ area on the imier side o 
 a.it.'nor border mdicates the surface of contact with the jugal 
 
 The extent of the overlap by the pterygoid is well mirl fi 
 
 fCthef ™'i \r ^^ the flange by a LrfL'e which exte,; * 
 
 from the top of the flange for more than two-thinls of its lenL 
 surface extends over the flange from its edge and is roughened Iv^ ..tior 
 which me approximately at right angles to the free e.lge At its w 
 end It broadens abruptly below a conspicuous sunken area n t le 
 posterior marginal concavity already described. 
 
 The head of the quadrate in an undetermined species of Tr-ichodo 
 has^elsewhere' been referred to as movable in the cotyl .s of the sou m.^a 
 There can be no doubt that it was firmly fixed in position ad mm n4l 
 in the genus now under < escription The fict th, f .. ho ' ""mouitJi 
 
 the squamosal descended for ^me ilishi^i^ ^ mi^Sv'uS Z 
 he anterior border of the quadrate below its head is ufficien to p^ 
 that the quadrate was stab e at its upper end The vrv ,>vtVn!il i '^ 
 
;j3 
 
 MiamirtmoiU of QmiilniU nj Kdmontiimunin {jxtriitijiu. Cat. .\o. :'JS!)). 
 
 Mil 
 
 Length of (iiiiKlratc in a straight lino 
 
 Muxijniim breadth (antcrf)-iX)stiTior; of cxtrrnal surfac'o !ii«)Vf (•oniait with riiiad- 
 
 ratn-ju({al 
 
 Horizdiital distance from external surface to ({ri'atest exteii-iim inward of (lanite 
 
 connecting with pterygoid 1 1; 
 
 4L'(J 
 
 (t.t 
 
 the 
 rd 
 
 I >Kure 1<. I^ttpteryR .id of EdmontoaauruH, fat. \o. 2289; J natural si' A, exter- 
 na aspect; B, internal uapect; 6»;i,surfnoeof contact with process of basisphenoid; 
 ep(, with ectopterygoid;mx, with maxillary; pal, with palatine; 9, with quadrate. 
 
 Pterygoid. (PL). Figures 3, 13, and 17. The pterj-goid is a thin 
 bone of complicated shape in contact with the quadrate, basisphcnoid, 
 palatine, maxillary, and cctoptcrygoid. It piubably also effects a junction 
 supero-antenorly with the vomer. 
 
34 
 
 and shallowlv concave '"'"Parativclj short l)a.so which is l)roa 
 
 .•api.n^upw::;.;''^^:';;:;,;:;! j'r'ij'fiV'c '' ••-"<':»--• «-• -- 
 
 ■naiii portion of th.- I.., r.nd r-nk it? ' '^','"♦'"4^'' '» ^hr- piano of t 
 
 of th.. c,,,u-..rKinK HaniV T.W. l/,i ''"r^ '"i J""'< "Pi'"'' P-rti. 
 
 «li>'-t.-.l l.a<kwar'd fniorJ n'lrd than"'''-^ " ""■"" '' "' 
 
 S,,i:/':i::;;"\';;^SriU;lrrvr^^^ 
 
 tlio dm,;,'. '" ""I!"'"!}- m"»t pto(,u,li.„t, a„,| ,h„ baso ol 
 
1 
 
 and deeply 
 lind with a 
 I is l)roadly 
 
 ivon off an 
 
 ion directed 
 
 Internally 
 
 aJ)ove and 
 
 nd narrow 
 lane of the 
 uterior one 
 Tnal anfrle 
 l<'iiKtli pre- 
 ward, and, 
 live. 
 
 lie stouter 
 me general 
 oiongation 
 •al ])()rtion 
 ige is also 
 I its inner 
 •ity of the 
 into three 
 K.derately 
 itinuation 
 ■e, deeply 
 terior one 
 ' posterior 
 
 <'Xtensive 
 ler to the 
 pterygoid 
 so as to 
 the hone 
 e slender 
 the head 
 ige of the 
 i)r border 
 bin edge, 
 is rugose 
 to. Still 
 stout, is 
 )r border 
 ' base of 
 
 surfaces, 
 forwarti 
 nd ends 
 r margin 
 laxillary. 
 
 35 
 
 Between this second surface for maxillary attachment and the lower part 
 of the overlap of the flange of tlie quadrate is the moderately large surface 
 for the external application of the posterior expansion of the eetopterygoid. 
 Above the contact with the maxillary process, for the full height of the 
 ant''ri<)r wing of the pterygoid, is thi surface tor the palatine which pa.sscs 
 externally back over the pterygoid for a varying distance from its anterior 
 border. 
 
 At the midlei'^ch of the superior bonier, between the wings, facing 
 inward and backward, and occup.ving the upper <'nd of the posterior, 
 internal enclosure between th>' posterior flange and the jxisterior wing is a 
 rugose, coi.eave surface, oval in outline, which grasj)s the front lower 
 convexity of the j)rocess of the basisphenoid. 
 
 The forwanl end of the anterior wing of the pterygoid is not complete, 
 but here the bone thickens slightly downward and supplies a roughened 
 narrow surface, diri'cted forward and facing inward, which apparently 
 indicates the union with tiii' i)ack termination of the voini'r. 
 
 MffisurrnieHts i>i L* I! I'tirifiiniii itf Kihmiiitn^iniru^, Cat. \(t. J/S!t. 
 
 Mm. 
 
 Miixiiimm length iilxivc iiiiii>crfc-ci uiilini-MiiMTidrly i :t."i7 
 
 .Maxiimiiii length below 1H4 
 
 Muxiiiuiin vcrliciil. aiitcriiir liciKlit iihovc hasc-livcl 'JliS 
 
 M:ixiliiiim vertical. iiDslcrior liiinlil above li:iM'-lcvcl L'l" 
 X'crliral height, alnive base-level, of superior border beliiml surface of coutail 
 
 with basisphenoid i)roei'ss 14'J 
 
 I'dlatiiic. (I'al.). Fiijuirn .3,t.i,aii(l 
 IS. This element is somewhat trian- 
 gular in lilt eral out line, is highest near 
 the front ;ind narrows downward and 
 backward to the nejirlystraightba.se. 
 It is thin anil i)late-like iind when in 
 position is almost vertical above the 
 postero-superior border of the maxil- 
 lary. It is sutunilly united to the 
 iiiiixillary, the jugal, ami the ptery- 
 goid. The anterior border is sluil- 
 lowly cmarginated in its ui)per half 
 to form the posterior curveof the pos- 
 terior nares. In the lower half of the 
 border is a roughened sutural surface 
 fjicing forward and slightly outward 
 and (htwnward for conta''t with the 
 jugal in the infero-anterior angle of 
 the orbital rim. This surface has an 
 irregu! '•- oval outline tind is about 
 twice a< high as broad. Hehind its 
 contact with the jugal the palatine 
 "'•*" fits on the narrow postero-superior 
 
 FiKurc IS. Hight palatine of Edmontosaurua, border of the maxillary back to and 
 
 l"l„^";,J!i*»' J; "»'•}">' '*'?'' A, outer aspect :pxt,.nding sUghtlv on to the pos- 
 n, innpr aspect, J, :,urfaif uf runlacl with juKul; . ■■■ r. i 
 
 mj, with maxillary; p(, with pterygoid. tenor maxillary process, from here 
 
 B 
 
My 
 
 toward tl.c-frrt a unm.k\1iminiLi^^^^^ "f overlap L.-ing ^rraf. 
 
 intervening ^ "PParently does not reach the vomer, the pterygoi,! 
 
 .^'Ifl.V 
 
 Miiximuiii \xv\iih\ of riKhl iiiilalitie •^'"'- 
 
 Maxnuu... 1,.„«„, .,f ,,,„, „.,^,.,;,, ,-;-;,„,-,„,.,; Wr,i;.;.l lin^^;,!.,,., ! ! ! ; ; i;!^ 
 
 Ectoplerygoid. (Ept.). Fiaures 13 ami to Ti,;, i • . , 
 
 and overlapping c'c^'S in a WlTn-*^''"^ "^ '°"« ^'^ '"'«'' -'^ - thin 
 wardly thieicened area which fits into 
 the postero-maxiUary notch, and comes 
 between the maxilla and pterygoid in 
 sutural contact with both. In lateral 
 outhne It is broadest behind, narrows 
 rapidly forward for one-third of its 
 length, and is continued narrowly for- 
 ward to Its anterior end. Its external 
 surface is gently undulating. Its ante- 
 rior two-thirds of length lies closely in 
 the postero-external concave area of the 
 maxilla on and above the shelf formed bv 
 the horizontal ridge extending back from 
 the maxillo-jugal surface of contact The 
 
 upper and lower borders of'the'bone, . ^Kurc 19. Left ectop.crygoid of E,l.n.,n- 
 
 :)aden posteriorly TZ,""' ''"*; »"•• ^-^^' * '«""'•»' "i"' 
 
 ;« *1 '"^"J"!.), ■V<""Pr"spo<l; H, inner aspect; m J- surficf 
 
 fit into two groove^ in the'maxiii;:; t; ^ ~^;^^ I^uS^; -^r^?.^ ^I^^" 
 one m the lower surface of the postero- *^""'- 
 
 7th mTxiCv Hdgf HerTth";b'';f tt-T"'"-' ''"'^,' '''' P^^-- «""' 
 border and fiHs the m.xilkrv ^""V^ickens inwardly below the superior 
 
 process internally Vo a^Se^xtentBeS't J '^' T'''"'^'->- 
 
 face of the bone is excavate.I tn fif „i *^*' thickened part the inner 
 
 the posterior enS of the mxil arv pZlrW^' ""^^ '^^^^'^^'ty "^ 
 the pterygoid. maxillarj . Posteriorly the bone broadly overlaps 
 
Mm. 
 I.ti 
 IS'i 
 
 B 
 
 Mm. 
 IINI 
 
 ■.':! 
 
 Miii.-'iin III: ^^^ iij Lift hlilnjili niijiiiit nf SiMTimni, ( ',it. \ii. .'.'s:i. 
 
 l..-.|illl!ltlHl Irtllflh 
 
 K-.tiiii;ili'<l iii.iMiimiri lirriiilili tliiiulit i iiii.>iiriiiily '. ... . 
 
 TliMkfics-. iif liimc wlicrr il lill.- the i)ii>liT(i-iii:i\iil,ir.v iKJlch. ....... 
 
 .\viniK'' tliiikiics.i (if liiirii' clsrwlicrc .' ,j 
 
 Vomir. (V.). Figures. Tlii.-^ clprncnt is known only from ii -ni:ill 
 poitKin (lisc'losfd toward its ...itcrior ond in the .spccini("ii coll.ct.d in 
 l!tl2 (Cat. No. 22H8j. The vomer has not been found with th.' di.'-ar- 
 liculatcd skull, l)clotiKinir to ^hcski Icton collectpd in litKj. It apparently 
 however, eonnected in front, with the niaxillaries on the inner side of the 
 anterior maxillary proeesses. and behind with the ptcrvtioids on the interno- 
 superior surfaei; on tiie heifjht of their anterior win^s, "and had an estimated 
 lenjlth of 38") mm. 
 
 The portion of the vomer seen in the 1912 .speeimen is 125 mm. Umn 
 attains a maximum breadth of 20 mm., and lies in the midline of the >ku!i 
 III the posterior half-length of the narial openinji on a level with and midway 
 between the upper border of the lower premaxillarv limbs. It is broado'l 
 at midlength, narrows slightly forward and much more .so backward, 
 so as to have an anterior breadth of 10 mm. and a posterior one of (i mni 
 In front it ends abrujjtly in a transverse break so that the >hape of the bone 
 at the maxillary eonnexion is not revealed. Behind, it eontinues into the 
 matrix of whieh as niueh has been removed as is at present pos..,ihle. To- 
 ward the front what appears to be a median line of division, traeeabje 
 for a_ short distanee baek, surk^sIs a eoaleseei :>e of an elemental pair. 
 
 The vertical inner surface of the laterally con-spressed anterior maxillary 
 I)rocess in Edmontosaurus is rugose along the whole of its length in advance 
 of a narrow, horizontal, shelf-like j)rotrusion, projecting inward from the 
 hinder part of the process, for the support of the vomer from Ix-neath. 
 lliat the vomer passed forward l)eyond the anterior maxillary processes 
 is probable judging from the appearance of the inner .-urface of these 
 proce.s.ses which are rugosely striated to the tip. In I'ro^mirolophus a 
 shallow groove is pres<>nt on the inner side of the superior l)order of the 
 lower premaxillary limb beneath the anterior end of the narial opening 
 ;''.".' J"^* Ix'hind where the lower linil)s separate for their backward ascent. 
 1 his groove in Prosnurolophus marks the position of the attenuated anterior 
 en( of the vomer, and it is probable that the vomer of Eilmonto.^aurus 
 had a like slender termination in advance of the maxilhp. To all appear- 
 ances, therefore, the vomer remained narrow between the anterior processes 
 of the maxillaries, separating them from each other by onlv a short trans- 
 verse- distance. 
 
 The shape of the posterior termination of the vomer is unknown. 
 ()n the inner side of the narrowly compressed ridge forming the most 
 (■levated part of the pterygoids forward is a roughened, transversely 
 concave surface on which the posterior end of the vomer appar- 
 ently lay. Whether the vomer bifurcated behind and reached the ptery- 
 goids on either side of the median line in this manner, or united with the 
 pair by a horizontal expansion has not been ascertained as yet. Judging, 
 however, from the distance apart of the pterygoids anteriorly the vomer 
 liad a posterior breadth of about 50 mm. Its estimated breadth between 
 the forward end of the anterior maxillary processes i? about 10 mm. In 
 this gei.us the vomer appears, therefore, to have been slender thioughout 
 and devoid of any considerable expansion. 
 
IS txtrimt'lj loiR. Ihf ronvp.KniK raini moot in n short hcrizontiil 
 .s>'niphy«8 an.1 are t-mbra.-.-d in fn.nt hy tho unpaiml 
 .1 ontary l„,n<. The rami are ,icepe«t at their midh-n^tr 'n atta n 
 h,.,r inax.inum l.readth at about wo-third.s of their I.^S frn 
 h,. fron where the eonspieuously h,^h eoronoi.l proee s i^ develop T 
 In lafral aspect they have a nearly straiRht or sliKhtlv undulating in erii' 
 out me As seen from above they are bow-shap,.,l with an inward , e 
 
 me..t. and less so behind where they are some distanee apart Km. I, 
 ramus eonsjsts of a .lentary, which is edentulous for about WeiKld 
 of ts l.-UK h in front, a suran^ular. an an«ular, a splenial an ar r? 1 
 an. possibly a pr.artieular, but whether this ..lenent is ee ai K , r.' "e t" 
 »'"•' ""» ' » "-rtained. The d.-ntary forms ,he ^reat-r ^^t' • 
 
 ''I' 
 
 ^^^^mm^ 
 
 Ar 
 
 - .. , 1 'i • • >■ 4 . '. 
 
 Mi 
 
 Dn 
 
 V 
 
 Sp 
 
 Sa 
 
 M^^^^i 
 
 nijr~ 
 
 ramus of the other comparatively small eh'ments. •■omposi,,., the hind.r 
 en<l of tl... ramus the surangular is robust an.l much th.. brKest th,- 
 angular ,s lon^ and slen.ler, and the articular the small cs 'Ss iV, ^l 
 
 sm- 1 . t h' -^ '"l'''''- Pe surauMilar supplies the lower ami , er 
 su faces at the hm.ler end. The articular lies above th.- sur-uiL ar 
 . ■«;.;.•.> It an,l the spl,.nial „„d to a limited extent is exposed exi -f.aHv 
 a .o\e the surangular. The dental magazin.- is nearer the nosterior n 
 tl.e anterior end of the ramus, a.ul is for the m,,s pL n't , ,1 ^tl v' 
 poserior ha -length. The e.lentulous portion of he lentary is onh- 
 siiKhtly 1,-ss tluin on.-third of the length of the ramus. ' ■ 
 
 ...M.! 'te isr'ir'L/I- Tn'? "^ Y'"*:''/^'" '"'""'"''•' »>-ti''"lat"« with the 
 1 .« u- ■ '*." ^!'''>' «*»"'•* 'listance in advance of the angle of 
 
 i"V ■., ^' '!,'T'""'' P"»".P''».V '^y the surangular, but the ar fcular 
 m ul uhr f fs .H 7 ' '"*"■' '"t7.""-^"P^riorly into its formation. The 
 maiulihulai fossa is of large .size and is confluent in front with the Meckeli'in 
 
 dent'rv 'tIh 'f"'"" '"''"'^f ^""7^''^ '"^"""••'>' "" ^he inner surfa 'o he 
 
 en arv .,n 1 '^ " 'T''"*?"^ externally by th.- coronoid pro.-ess of he 
 
 t ini .dlv bv^r^"/''';' '"^^™!-Jy.''>' t'«' 'io'tary and the surangu lar! 
 
 ana internally by the dentarj, .splenial and angular. Antero-inteniallv 
 
:«> 
 
40 
 
 r ,,•. ""'■''"' the lotiKth of tl„. l„„„.. The .•oron„i,| pn.c.J is 
 
 at.l> thiik Ih(< odentuloUH part is (..mparativflv tliin, with a ifra(lii..llv 
 l.-.ss..nmK depth forwar.1, an.l lonKitudinailv io «■ v i„t3 v \ 
 curves abruptly mwar.l in front, with a i..w.rin« of the «m" ■ I, r order 
 o meet U.e dontary of the oppomto side in a iiganTent..us .•,,, Lex , , e , i 
 the pmlentnry. The mandibular fossa ex.avafs th<. ...r no ,r, ," 
 behind, and .nternaliy is continuous with the >I..keiian7 •, w i'^ 
 .sens m depth m its forwani course n.'ar the lower l...r.l.r ,f tl e m . 
 u^id .l.sappears in advance of a point in line with the front en of I .l 
 majja.ineHeh.nd the mnKazine the ,|,,.tary en.ls in a h ra II v 
 con,presse,l, ,M,inted process, internal to the ^nandibular f J T li^ 
 process IS covered .,n its inner face, and embraced above, by th.- anter 
 end ..f the spl..n,a Posfrh-rly beneath the .M.^-k.-li ,n Lm.ov i^ a 
 narrow surface markiuK the internal application of th an^ • .'.s f. 
 erWIv ."1 " ':;""'i "?^'y.''<>"^''th the midlenKth of the n ia .. 1> „ 
 ter orly below the dentary is transv.Tsely broad, thin, and obt uselv ,oi,, e.l 
 at it.s termination, underlappiuR the suranguhir so that thf ,;„•'. 
 Thnir "[/""'' ..Yont nuous on the upp,.r front surfa,-e of the rani.l 
 T "'"^J«" •"'.V'nphysial surface is deeply groovcl from front t , Ik' 
 The dental foramina, corr. ponding in nuniber to the vert c I I'ri of 
 teeth, are conspicuous int.-rnally following the lower curve of th nag , n 
 At the anterior ..nd externally is a rathcT large foramen behind M n^ 
 
 nng'zinr^tr ::';h?"h"V'"''«"''^'' '""'t^'H '""••^ *» ""■ f-ni :. 
 
 of tllffbone. '"■*'' " "*■ "**"''■ ^"'•""'""i i» •■"■ '"iter face 
 
 wifh^*-?.,!!"" i'fi"*"?' ^'T'"'' "r f'^-tJ'-^-iKht "rfc ■ -ine verti.-al series of teeth 
 H th four or five teeth and sometimes the st .,f a sixth in each s ■ ■>-. 
 
 The inciy.dual teeth are largest at the midh-ngth of the ag / . , d 
 
 storterZV'"'V"r'^lr'*'"''" ^"^ "^ '*' *'"" P-f^"'"' ""^"« >-i"g ^n "i 1'^; v 
 s orter but on y slightly narrower than those in front. The inner en «- 
 
 w th r }"n"''^"T' '"^*"'»' ''^^'"■'■*' "■••• "^"'•'•V I-^senge-shaped in o . C 
 ^ith the onger diameter vertical, and fit closely together (minvlZhUv 
 ma mosaic which is almost half covered from below by the Xc'lar 
 
 Zn ♦."■'■'' T ''hT.^s 230 teeth in each dentary, this being in/mv | ss 
 than the number (406) ascribed to Diclonius mirabilis by Cc in hU 
 description of that species in 1883. "»c oj ^-opc m his 
 
 Areasurements of Left Dentary of Edmonlomun,.,, C„i. \„, jjsu. 
 
 I'<>ngth about Mm. 
 
 n&iT ? • '"'•"'^^"Kth andmidhcighi of '.ientarmnKazino; .' ^?j 
 
 loTer''b^X."''^'' "' '""^« '"^'"^ "' '-th, af „udk.,.g,h of maKazi,;,; abov,. "^ 
 
 D2?lnr''/,^r'"J"f '" '^^■T^ Of first'vertical' series of teeth: ! ! ! ! ! J^ 
 
 lV^l.h f !i ' ? ?^ <■""■<"'."»' Vr^"'^ above luwer borrier of .lfi.lur> .^7 
 
 Length of dental magazine at its midheight "ti'iurj 297 
 
 300 
 
11 
 
 7S0 
 58 
 
 190 
 
 297 
 
 ami 
 
 riMtcrior ili'plh ol' iiuiiii/Mw, iiIhuii 
 
 Aiiliriiil ili'ptli of iiiiik:iziiii'. iilmiil 
 
 l)i'|>lli of liiuKa/K"' :i> llH liiKllriiKili. .iluiiil 
 
 I'l.-lirior liri'.iillli nf iiilliiiK Mirfan' ni iiiili, mIuhii 
 
 VntrrKir brrailtli (if nilliiiK "iirf.nc nf inili. .ilimil 
 
 Urracltli iif I'littiiiK siirfiiri' of tnlh :il ii. iiiiilliiiulli 
 
 s» 
 
 ii:. 
 
 s 
 
 with 
 
 llllllC 
 
 I'mlcntnrii. (/'(/.). In ihr t\|ic of Kilniiiiilnsdiinis this Imhu- I^i In 
 lilacc hut is inustly ciniccalnl hiniath thr |>iiriiaxill!iiifs. [is frmit. 
 honlcr i- itijurt'd and tlinniuhinit it sccins tn havi' hccn (h-lurtiMl ami 
 riu^liiil. With the furlhir ninoval of matrix from thr -pcfimiii. if this 
 proVf fi'a-ihli', M)mr uuicral idea of the proportions of thr hon<' may he 
 uaini'd from liclow, hut at prixiit its description is not po— ihic. It was 
 
 hroad ill corri'sijoiidriirc with tin' (rnat exterior expaii-i f the pre- 
 
 iiiaxillaries, and appears to have l)een moijerately thin in front with a 
 development of the notches aioiin thi- front horder so usual in tlio lladro- 
 sauridii'. 
 
 In the paratype of Kdmonhifniurus tiie predentary as will 
 preinaxillaries were not found. 
 
 Siimnijiilar. (Sit.}, h'liiifis .1, ;, .'(), ami /.'. In comparison 
 
 ilie annular, articular, and spleiiial, the suraiiKular is a larjie, rolmst 
 
 with an extensive attachment to the dentary. It. in coiijuiK'tion with 
 the fiiidular, articular, and sph'iiial, adds consideralily to the leiiuth of 
 the manililiular ramus, and it is principally through this hone tliat the 
 attachment of the mandihle to the (piadrate is cfTocted. 
 
 The stiraniiular articulates in front with the dentary, postero-.superiorly 
 with the articular, and laterally on tiie ;nner aide with the angular. It 
 consists of a somewhat ohhrn^ main portion, lonner tlian hroad, hroader 
 in f'diit than tx-hind, and thick [losteriorly in contrast to the anterior 
 half-lenjjth wiiich is thinned liy havinj upper surfaci excavate<|. The 
 
 main portion (if the hone posteriorly - a hackward extension ^n ilie 
 iiiiier side which thins to the rear, faces upward and inward, anil, when 
 viewed from ahove, curves outwardly in outline to a broadly rounded 
 termination. The supero-exterior horder of this posterior extension is 
 continued forward on tiie upper surface of the main portion as an iijiwardly 
 directed flange which thins to the front where it ends ahrujitly a short 
 distance heliind the concavity in the anterior upper surface. This flanije 
 is close above, and curves in conformity with the inner border of the hone; 
 it has a vertical inner face and a .sloping outer one. Hetween the base 
 of the flan-e and the inner border of the bone is a narrow horizontal shelf 
 which extends forward with increasing breadth for a short distance bevond 
 the flange and is carried back on the inner side of the extension as a gi-oove 
 best defined posteriorly. This shelf and groove mark the upper limit 
 of the surface of contact between the angular and the splenial. Antero- 
 exteriorly there is a prohmgation of the main portion of the bone upward 
 and slightly forward which end^ slenderly above, reaching a height of over 
 110 mm., above the general plane of the lower anterior surface. This 
 prolongation is laterally compressed throughout, and at its base is directed 
 obliquely backward is a ridge toward the vertical flange, bounding the 
 anterior concavity externallv. 
 

 B 
 
 A, e^S a p^^"^ ' , r r'^^'T;"*"*'"^"^' • ■"•■ ^o- 22S9; S nu.un.I size. 
 
r.\ 
 
 which apimrcntly imwHcn forwanl on thi- inner nulv of the flimnf uml is 
 HupportiMl l)(«l(iw hy the nurmw hi)ri/i>ntiil Hh»-lf Ix-twi-cn tltf Imxc of thi- 
 flungr nml the HUtiiritl Miirftict' for th<> angiihir. 
 
 Th<> upp«T (turf lice of thi- lionc i'xt«Tno-pt>8ttriorty in shiillowlv ixcuvatcd 
 for the rcri'ption of the ureatcr iMirlion of the lowir ind of tht- (inadiutr, 
 
 the ri-maininK part of th tyhis luinK ciipplltd hy the articular. Thi 
 
 rontril)UtionKivin to the <otyhi?' hy tin- siiraiiKuiar pai*MK inw.ird ami iip- 
 wiird on to the flannc and a* difincd in front hy a low, roiindi'd ri'litc 
 which runs tranMVcrncly outward from the fhmne near tix anterior endinic 
 to the outer horder wliKJitly in advance of the poHteroHXterior anKJc ol 
 the main portion of the hone. 
 
 MttiHiirrmiHlK iij Hiyhl Suriinyiilnr nf EihiiiDiUmvirtin, t'nl .Vo, ,'.',s,'/ idisiiiliiiiliitnl 
 
 Liiigth i.f Ixini' iiirii.-iii-inl :il(iiiK lli. ctirvr nf its Inwi-r surfiiic frmii ilir front iH.rdi-. 
 
 I<) llii' liriiiiiijilii.il (if till' |hi«ii'rjiir r\tciiMiiii 
 Hrcailth iit iiiji|||.injili 
 
 lli'idlit lit iiijillrriictli frmii Inu.r ^urfun- tn tup nf iiiiiliaii lliiiiur 
 Hiickwiinl ixtiiiHiiiii nf -utaiiKuliir hi vorul iiifirii-|ini.tiTjiir liriiiiiiiitinii of ilnitiirv 
 'I'liiikiiifs. frniii limir to ii|i|iit iiirfiin-, nf iiiiuti pnrlii.ii nf iiiiilhriiiillli slinlillv 
 
 lichiiiii tiuilli'iictli 
 
 Arliriilor. (.I//, Fiiimr.i :0 ,inil J.i. In this species tlie articular 
 is as y(-t imperfectly known. In the type skull. Ctit. No. •J2K8, it is repre- 
 sented in tlic richt inaiidihular ramus hy a small fraumeiit in place hetween 
 the smaiujular and the splcnial ahovc the pusteriur terininatinii of the 
 angular. In the disarticulated skull, (at. Nu. 22.S'.». the niilv part of it 
 
 Mm 
 
 J! Ml 
 M 
 • it I 
 
 117 
 
 :il 
 
 S/. 
 
 1> 
 
 B 
 
 \ v> 
 
 Kijfure 2:t. riirtinn of Wt artiiular i.f Kdinoiiioniiurus. Cut. No 
 22S9, in pluie on llie sploriittl; J niitural »iif .\, I'ltiTnal aspcrt; li, 
 antiTHir a»p»Mt in outline; (', piMtrrior UKptTl in outlim-. Ar. iiriiiu- 
 lar; q, Kurfam for contact witli quailrate: fu. .~urfarf (or .^uraiiKular; 
 Si), spk-nial; ap, aurface (or uplenial. 
 
 remaininR is a piece of irregular shape, ')') mm. in maximum lennth. .')! nmi. 
 ill depth hehind, and 21 mm. in hreadth antero-superiorly, adhering to 
 and in its proper relative position to the outer posterior surface of the 
 left splenial as shown in Figure 23. The fragment in the type skull, so 
 far as its smallness permits, corrohorates the larger portion in the second 
 skull a.'i regards shape and posiUun. 
 
44 
 
 .3 h,. n.main.„K on.-thinl ..f the ,l,.pth of the l,„no 1 mt., mitw ir 1 
 aiu supplyiriK a fro.- surface wliieli i„ its anterior nart is « i.rl t v ' 
 
 |U. e.H.stiUrtes the small c,„nril,uti..„ .,f CariieE ^, 1 ^' tu mlldar 
 e<)t.\liis. The narrow lower bon Cr of the artieiil-.r fits int.. ♦ „, 
 .n t^e suranuular mentiozjed in the desiript^i;,n':J''^.S -o^^a ' ,?^H^ 
 above th.. post,.r..,r end of its surface for th.. attachment f ll a Sr 
 r-ontinuuiK l)ackward the articular probai)lv ros,. sti hi. "" '"'*-'"'f- 
 upper bonier of the splenial, as r.'stored h^^ureV iw '^ ''"i 
 
 t.. s,,me extent on the shape of the articular i;^;!?;;;Sj^;^* tK ui!;^ 
 in advance of is ct.ntnbutiou to the cotvlus, in vivx, of t ,• fact that her,^ 
 .s a space eft betw.-en the splenial and" the suran^ndar vhel the f 1 . s 
 are u, ,,os,tion. may have continued forward as i^iv.d t V thin , e 
 b.'twe,.n the mner vertical face of tlie flaURe of th ^ura lul-.r , t e 
 
 ^ontal shell of the surannular. However, the possibilitv of the nrese, 
 
 of a prearticular should not be overlooks. " ' 
 
 "^L.. 
 
 n-..„rl'?"'^ -'4. Left spleniul of Edmontosaurus, Cot \o ooso- i 
 
45 
 
 In advance of the <urved process the bone narrows to a pt.int. In the 
 posterior two-thinis of its lenRth it lessens but sli^l.tlv in depth backward 
 In each of the tlircc splenials available for studv. viz., the two lu'longing 
 to the naturally disarticulate.1 skull, (at. No."228y, an.l the right one 
 o. t at. ISO. 2288 the posterior end is missinR, but, jud(jing principallv 
 from the shape of the surangular in this region, it probably terminated 
 with a nninded lateral outline as restored in the above figure. The bone 
 is curved in conformity with the curve of the angular and surangular 
 so that its inner surface is moderately concave in a longitudinal direction 
 
 its superior border toward the front rises over, as alicadv *tat.'d 
 aiKl embrac's the upper edge of th.- dentary. Its pointed anteri(.r extension' 
 reaches forwan and is applied to the dentary below the hiiuh-rmost portion 
 of the row of dental foramina. The surface of contact with the dcntarv 
 extends slightly back of the splenial's half-length. 
 
 Th splenial reaches farther back than the angular and is in contact 
 inferiorly with it for nearly the whole of the hitter's half-length The 
 surface of contact between the two is broadened and, with the increase in 
 area, streng hened by a ridge which ext<>nds outward along its length 
 causing the lower external surface of the bone to be decidediv concave in 
 a vertical direction. The upper surface of this ri.lge receives, and supports 
 trom below at least m its more posterior part, the lower border of the 
 articular. Anteriorly there is a space left between the splenial's pointed 
 extension and the angular which leads outwardlv into the mandibular 
 Ossa. Postero-externally the i)one for the whol.-'of its depth is appli.-d 
 to the articular and passes beneath it by means of the ridge just mentioned. 
 
 Minsiiiriiii „ls of hfl Si)l,„iiil of Kdmnnli,sni,ni.t, Cat. \o. ^>.'S!) ((ii.«irliniU,l,d 
 
 skull). 
 
 iA-nglh of bono |>rcscrv(Hl. iiit.ii.-<iiri-<l .ihinft ihc inner curve ' '"!ii 
 
 l.stimatc(i total length TJl^ 
 
 Depth at midlength .I? 
 
 licngth of autural siirfaeo of contact witli ilentarv i^' 
 
 Maximum breadth of same " ,." 
 
 lb 
 
 .......„,.,„u.u.-., Cat. No. 2289; J natural si»e. 
 
 rfi, surface for dentary; no, for surangular; 
 
 I'iKui«2.'>. Riglit angular of Edmontosaurusi 
 external ahpe<-t; U, internal aspect; ' 
 for splenial. 
 
 Angular. (An.). Figures 20 and 2o. This bone is long, narrow 
 and thm, and is m sutural contact with the splenial, the surangular, and 
 
46 
 
 the dentap' It runs forward from a short distance in advance of the 
 hinder end of the surangular, on the inner side of that bono, to a point 
 »^*h .K •''r Hu""^. *u^^ Meckoiian groove, presumably about in lino 
 with the niiulongth of the dental magazine. In lateral aspect it is bent 
 at one-third of its length from the posterior termination, being straight 
 and inclined shghtly upward m the hinder part, and horizontally straight 
 in the two-thirds forward length. Its greatest depth is at the bend whence 
 It narrows forward and backward to its pointed ends. Viewed from 
 above It has a flattened sigmoid curve resulting from its close application 
 posteriorly to the convex curve of the inner border of the surangular, 
 and anteriorly to the longitudinal concavity of the lowermost inner surface 
 of the dentary. Superiorly, for nearly the whole of its po.«' - half- 
 length, It IS in contact with the lower border of the splenial n i «. 
 25ii, representing the inner aspect of the right angular the 
 Scatld" *''^ ^""^ ^'^^ *^^ ^^'^^^ elements above mentioned are .kany 
 
 Measurements of Right Angular of Edmontosaurus, Cat. Xo. 2J8!) {disarlkulaled skull). 
 
 Length of bone preserved, measured along the inner nin-e '^'"™, 
 
 &8tiDiate<l total length -.- 
 
 Depth at bend '.' ' 
 
 Ma-ximum horizontal breadth of sutural siirfaco for Mirang.ih.r in.ax. thi.-kn.-ssj '. '. 1.5 
 
 Outer Openings vf Skull. 
 Supratemporal Fossw These openings are of moderate^ size, ami 
 
 ^nrL r^ ^^ -^u' "° "^''u'' f'"^^ °^ *^^ extremely narrow longitudinal 
 parietal ridgo. They are subtriangular in outline, more than twice as long 
 tV'l-i "'"■'■"'I'y rounded behind, and end squarely in front wh(>re thov 
 mLni '■ * *' "T ''^""dfd externally by the postfrontal and squa- 
 mosal (supratoinporal arcade), posteriorly by the squamosal, anteriorly 
 by the postfrontal and parietal, and internally by the parietal and squa- 
 mosal They are floored on their inner side by the parietal, prootie, and 
 to a limited extent iilso toward the front by tne alisphenoid. Inf.To- 
 external ly they open beneath the supratemporal arca.le into the infra- 
 cavities ^'^^^'' ^""^ confluent infero-anterioriy with the oH.ital 
 
 Infratemporal Fossw. The principal feature of these openings is their 
 ex renie narnnvness in comparison with their height. Although narrow 
 below they lurome st.ll further reduced in their upper half where thev are 
 encroached on by the backward extension of the large postfrontals. their 
 lower end is withm the jugal. Anteriorly the fossu- are bounded by the p„.st- 
 ori.ital bar proper and the auKmented postfrontal; their narrow ut.p.'r 
 end is conhnod by the postfrontal and squamosal, and posterioriv th.-ir 
 margin is formed by the squamosal, quadrate, and jugal. They are'neari v 
 twice as long as the supratemporal fossa>. • 
 
 .knll^Sn"' ^f •"'''■• T''-*' ""■'?'*' ^""^ ^•^'^ '^'■K^^t of the openings of tl... 
 out line ui?b n" "f ^"'"f *• "' """"' ^P^'"'"P- Thoy are subcircular in 
 outl me with an antero-inferior extension downward and forward the 
 height slightly exceeding the length at midhoight. The anterior mardn 
 
 Is boimt n '\^''f'r'^\ Irl'^^™''"' '^"^ J"«^'- Superiorly the ope, fng 
 IS bounder! by the prefrnntal, fn.ntal, and postfr.,ntal, posterioriy l.v the 
 
47 
 
 postfrontal and jugal, and inferiorly by the jugal. The relative sizes of 
 the orbits, narial opening, infratemporal fossie, and supratemporal fossw, 
 may be expressed by the numbers 8G. 56, 25, and 24 respectively. 
 
 Post-temporal Fossce. In the occiput a deep transverse indentation 
 or groove runs outward on either side from beneath the backward extension 
 of the parietals under the lower border of the squamosal. This groove 
 for some distance beneath the squamosal (Figure 0) represents the post- 
 temporal fossa> reduced vertically to such an extent as to oe virtually 
 dosed. In its more external part the lower border of the squamosal has 
 an arched curve above the groo^ ^nferjojiy ^j^^ groove is bounded 
 by the prootic and ?supra-occipitai. A somewhat similar :ondition of 
 these fossa; is found in Iguanodon.' 
 
 Narial Opening. This opening has the form in lateral outline roughly 
 of a lengthened oval, somewhat flattened below, and more rounded in 
 front than behind, with a length nearly five times the height. The 
 anterior and posterior ends are within the premaxillary and the nasal 
 respectively. The superior margin is formed almost wholly by the nasal 
 and the mfenor one principally by the premaxillary. The size of the 
 openmg is proportionate to the great anterior development of the nre- 
 maxillanes. 
 
 Foramen Magnum. This opening is large in comparison with the 
 size of the bram-c, .ity. Its width is equal to half that of the cavitv at 
 the cerebrum and about equal to that across the medulla. It is nearlv 
 oval in outline, higher than wide, and narrowed slightly below. The 
 vertical diameter is 50 mm. and the horizontal one at midheight about 
 40 mm. It is bounded below by the basi-occipital, laterally by the ex- 
 occipita s, and above apparently by the supra-occipital. Its upper outline 
 IS sharply defined by the transverse angulation formed by the junction of 
 the descending roof of the brain-cavity and the lower surface of the supra- 
 occipital. Laterally and inferiorly its exact boundary is not so rleariy 
 niarked— being carried backward over the basi-occipital and between 
 the condylar protrusions of the exoccipitals. Viewing the cranium from 
 behind the opening is set deeply in the occiput with the supni-oreipital 
 extending nearly horizontally backward for a distance of fully 115 mm 
 from its upper rim. 
 
 Cranial Foramina. Figures 26 and 37. The openings in the brain- 
 case for the exit of the various nerves are well preserved in the naratvnc 
 of tdmontosaurus. Their size and position are as depicted in Figure 20 
 gmng an external view from the right of the cranium proper. In Figure 
 2< showing the cast of the brain-cavity in three aspects, lateral (A), superior 
 (B), and inferior (C). the length of the foramina and their diioef ion tliroueli 
 the cranial walls are indicated. 
 
 The olfactory nerve opening (I) is bounded inferiorly and externallv 
 by the presphenoid. Whether the opening is roofed over by the frontajs 
 or by the presphenoid. or by both, has not been determined as no sutures 
 giving the desn.'d information are preserved. The side walls of tlic 
 presphenoid seem to curve inward over the opening, in which case the 
 frontals would contribute to the formation of the roof only along the 
 longitudinal inidhne. The opening is more than twice as wide as high. 
 
 ' IJuatrifnie noli; sur les .linnwuiriBM ili- H<.mi«»art. par M. 1.. UoHn. B::il M>i««s R.-.vftI .rm-h.T- 
 •e IMKiilUf i.iiii.. II, lM.t, pp. 2J4 in«, pl„ IX nmi X i ni t"T. 
 
 8329— 4 J 
 
 •:r,-!i.- 
 
48 
 
 :5!s trS - 
 
 t3 = ?* e t" 
 
 e i s ii 
 
 ^ O..S -S J » 
 
 «« = -..» 
 
 fc-i2. 
 
 ^te 
 
 
 
 1 x.s.sca.. 
 
 Wr 
 
 
 
 ^5 
 
 i 1 
 
 
 f -0 
 
 1 >.£§..>< 
 
 ^ 
 
 
 
 
 
 ^^^ 
 
 «t-a-3"> 
 
 ^B^ 
 
 
 
 1 B .. O C •"« 
 
 9^^l 
 
 ' P^V 
 
 w^K^^^^m 
 
 S.&Ha,g- 
 
 ^^K^^^^m 
 
 S uS--S>-" 
 
 ^m 
 
 11 ^ll;; 
 
 
 S^ - ci a . p 
 
 ^F 
 
 •3^ .^5 " S 
 
 r 
 
 
 
 
 
 
 
 «-3.:i.---aE 
 
 
 e 1-2 sJ 
 
 .Sf e 3 9 C g 
 
 
 
 
 ^fstyi 
 
 
 ^&)ol,s 
 
49 
 
 Its outlino .,., sr.'n fn.rn the front, is Hat Ix'low with a sliirhf ab 
 at midwultli. rounded at cither side, and hroa. 
 above so that the heitdit is least at tlie middle, in,| 
 the olfartory lobes, one at either side. 
 
 nipt rise 
 
 roadly lowered medially 
 
 leatiiiK the i).i>iti.in of 
 
 Piereinj; the rrani 
 
 uni from side to sid 
 
 lower part of the orbitosjilienoids is .. 
 line with the !interior end of the 1 
 
 le where it is narrowc -t in th 
 
 ige of I 
 
 by the 
 
 )ptic 
 
 I passa 
 )asisphenoii 
 
 eonsjdcrable si/e vertic.allv 
 
 This I 
 
 )as<a(je iieeu|)ied 
 
 ehiasma also eommunieates widely upward with the 1 
 
 eavity throuph the floor below the ^paee for th(> cerebrum- it 
 of, and at .a slijjhtly higher level than the pituitary d 
 con luent behmd. The extern.al openiiins .,f the 'pa-au.- a 
 the longitudinal axis of the skull, ami set at an .Minh" t., each ot I 
 
 nan;- 
 
 in ad\;incc 
 
 . Toss.'! with which it i> 
 
 pcniiijis iif the passijie are obliipie to 
 
 inn •"ach other in front, and f 
 
 Tl 
 
 liey are oval in outline and ne.irlv t 
 
 icinj: decidedly downward and f 
 
 ler. approach 
 
 openinfj above is 30 nun. wide t 
 
 wice as lonn as hi(rh. The ined 
 
 ■an 
 
 lateral openin^.s that the optic nerves (II i found exit 
 
 ransversely. It was by means of th 
 
 Behind and at a slijrhtly lower level than tl 
 
 just described, and separated from it by a bar of 
 
 •le transverse perforatii 
 
 i)road, is a large, almost circular forami 
 
 of the oculomotor (III) and trochlear (I\ 
 
 n apparently for t 
 
 bone about 14 ti 
 
 part of the decided 
 
 ) nerve; 
 
 It 
 
 im. 
 
 le coIDlMon exit 
 
 occur 
 
 eonca 
 
 lower, front portion of the bra 
 
 vity marking the lateral compi 
 
 in 
 
 the I 
 
 )ac 
 
 •essioii (I 
 
 if th 
 
 f the side walls of the 
 
 It (ipens through the upper part 
 
 H'ing about on a level with the posti 
 
 pituitary cavity (infundibulumi its u 
 
 tiing forward from the lower m 
 
 rior rim of the pituitary U 
 
 pp. 
 
 curvr' 
 
 irgin of the f. ramen is tl 
 
 n 
 
 un- 
 
 le suture defining 
 
 e upper limit of the front part of the ba.sisphenoid. ' \\hether tl 
 enmg is whol y withm the alisphem)i<l. or, as its jxisition suggests, boun 
 
 behind by the alisphenoid and in front by the orl 
 
 been determined, comjjlct 
 apparently taken plac( 
 
 itosphi 
 
 e coalescence between these two el 
 
 id h 
 
 as not 
 
 Behind the foramen for the thinl and fourth 
 what higher level and .separated from it 1 
 
 Cments having 
 
 cranial nerves, at a .scnie- 
 
 „ „• , , . . -•• .>y a siiace of about 27 mm., is .-in 
 
 op(;nmg of large size, the foramen ovale or trigemin.al nerve (\i exit 
 Ihis foramen occupies it.s characteristic p .sition in the reptilian skull 
 m fn.nt of the prootic It lies for the most part within the alisphen.,id 
 with th.- prootic bounding It posteriorly, and is a short distance .•d'ov,. th.- 
 hinder end of the base of the flange directed outward from th.^ upper 
 portion of the basisphenoid. Its outer opening is larger than th.' inner 
 one but Its greatest diameter is attained within th.' thickness of the bom- 
 where the size of its passage through is considerably increas.'d by excavati.m 
 forming a fossa. 
 
 This foramen is best preserved on th.' right si.l.. in th.' paratvpe .,f 
 Edmontos^aurm where externally it is longer than high, subtriangular in 
 outline and highest in front, measuring 24 mm. in length an.l 18 mm 
 in height-. On the left side of the specimen the opening has ben reduced 
 in height by cru.shing. Leading forwar.l fr.)m it anteriorly is an on.-n 
 channel or groove which marks the position of th.- ophthahnie bran.l of 
 the trigeminal nerve (V ) (s^ee also p. 52). Th." suture between the alisphenoi.l 
 and the prootic reaches the opening posteriorly from above. 
 
 In the floor of the brain-cavity, midway between and at a slightly 
 lower level than the tngeminal nerve (V) exits, are two small openings 
 
50 
 
 on., on L-ithcr side of the longitudinal midline of the floor, which mark the 
 oriRin of the abducent or sixth nerve from the ventral region of the medulla 
 l-roin each of these openings a long, straight passage leads forward with 
 a 'lownward inchnation mto the pituitary cavity debouching immediatelv 
 iM-low the hinder rim of the pituitary fossa, and in close proximity to the 
 foramen for the third and fourth nerves. The two passages are parallel 
 to each other and pierce the basisphenoid in its median elevation behind 
 t he pituitary fossa. I rom the position of the anterior end of these passages 
 It IS presumed that the sixth nerve, a purely motor nerve supplying the 
 .xt.inal rectus muscle of the eye, found exit also from the large am-rture 
 apportioned to nerves III and IV. ^ 
 
 The foramen for the seventh or facial nerve, behind the foramen 
 ovale, and separated externally from it by a surface of bone measuring 
 aimut 11 mm. across, is small and inconspicuous. A narrow but well- 
 dehned channel leads downward and forward from it toward the deen 
 groove beneath the flange of the basisphenoid, which terminates below 
 at the lower entrance of the internal carotid artery. This foramen pierces 
 the prootic as in the alligator. i « <^o 
 
 , ^^}i}^^ ^^^. ^'''* «f **i<^ seventh nerve, and distant from it externally 
 about lb mm. IS a rather large opening, the fenestra ovalis + the fenestra 
 rotunda which internally communicates directly inward with the brain 
 cavity by a small oval aperture, the internal auditory meatus, through 
 which the eighth or auditory nerve left the brain and reached the auditorv 
 organ by means of its various branches. Rising upward in the thickness 
 01 tlie bone from the passage between the outer opening and the internal 
 "*?u ^r^x.^ ''*''*^ PP^*^^ ^^''^*> apparently marks the position of the labv- 
 rinth. The semicircular canals are not preserved in the specimen (para- 
 type) nor has it been possible to detect any representation of other parts 
 of the auditory organ. The side wall of the brain-case is thickened inwardly 
 at this position of the labyrinth causing a marked convexity of the surface 
 ol the bone in the brain-cavity over a considerable area above the internal 
 auditory meatus. At about the middle of this convex area, at about 
 lU mm above the meatus is a small opening, between 2 and 3 mm. wide 
 connecting the large space within the bone with the brain-cavity 
 
 l<our foramina of rather small but nearly equal size occupy a definite 
 sunken area bounded below by the lateral convexity of the occipital 
 condyle, and in front and above by a prominent ridge which latter runs 
 upward from the basi-occipital behind the fenestra ovalis and continues 
 almost horizontally backward to the paroccipital process of the exoccipital 
 Ihis sunken area is most depre.ssed in front where it ends as an excavation 
 beneath the ridge. Of the four foramina two are close together in front 
 one above the other, and are overhung by the ridge and partly concealed 
 
 uL- i"" ^J^u^'^} ,1'^"^ •'^u*''^ ^''""- Anteriorly the ridge is sharp-edged 
 behind and about 12 mm. broad. The third foramen is at a short distance 
 behind the front pair, and the fourth follows the third at a somewhat 
 increased interval. The lower anterior opening and the two posterior 
 ones are m an a most straight line horizontally. The upper of the two 
 front apertures, slightly larger than the lower one, is the foramen lacerum 
 postenus transmitting the glossopharyngeal (IX), the pneumogastric (X) 
 and the spinal accessory nerves. The direction of the passage outward 
 through the bone for these nerves is obliquelv backward. The inner end 
 
i 
 
 51 
 
 of the passage is larjte and close behind the internal auditory meatus, 
 the external one is much smaller and opens under the ridge already mention- 
 ed about 9 mm. tiistant from the back margin of the fenestra ovalis. The 
 lower opening is for the transmission of the jugular vein. The passage for 
 this vein starts within the wall of the brain-cavity in a small orifice well 
 down in the medullary region some distance beneath the inner end of the 
 foramen laccrum posterius. It curves upward and backward through 
 the bone and emerges close beneath the common exit of the ninth, tenth, 
 and eleventh nerves, separated from it only by a thin partition of bone 
 so that the two openings are almost confluent externally. Near the external 
 end of the jugular pas.sage there seems to be a branch leading forward 
 within the bone, but it is small and its course has not been ascertained. 
 The opening behind the foramen lacerum posterius, and distant from it 
 about 8 mm., is the anterior condyloid foramen, Figures 2t) and 27, a, c. /. 
 The hindmost of the foramina, about 16 mm. farther back, is the exit of 
 the twelfth or hypoglossal nerve (XII). Its inner end is considerablv 
 larger than the outer one. 
 
 limin. (Figure 27.) 
 
 The brain-cavity of Edniontomurus is long and narDW but relatively 
 much broader across the cerebrum than elsewh(>re. Its length is slightly 
 li'ss than one-fourth that of the skull, and it is both actually and porpor- 
 tionately longer than the brain-cavity of Claosaurus anncctens as repre- 
 sented by Marsh's figure of the cast. 
 
 In the paratype of Edinonto.murus there is little distortion in the 
 cranium and an accurate gelatine cast of the entire brain-eavitv was obtain- 
 ed and reproduced in plaster, Figure 27, A, B. C. The cast includes the 
 nerve exits for their full extent outward, giving the diameter, direction, 
 and length of the passages, and the thickness of the walls of the brain- 
 case at any particular opening. 
 
 The shape of the brain-cavity probably does not give exactly that of 
 the brain itself especially if conditions were at all .similar to those found 
 in the Tuatara [Sphenodon pundatus) of New Zealand. Dendy' has 
 remarked on the great disparity in size in Sphenodon between the "brain- 
 cavity and the brain, which latter he found to be suspended in the cavity 
 by innumerable strands of connective tissue. It is reasonable to suppose, 
 however, that in dinosaurs the brain conformed in a moderate degree 
 tr the shape of the cavity, and this assumption appears to be borne out 
 b. the cast in which the various divisions of the brain seem to be fairly 
 represented as regards size and relief. In describing the cast of the brain- 
 cavity of Edmontosaurus, therefore, its dififerent parts will be referred 
 to in terms that would be applied to the brain itself. 
 
 In Figure 27, the cast is shown in lateral. A, superior, B, and inferior, 
 C, aspects. In it the principal divisions of the brain are denoted, viz., 
 the olfactory lobes, the cerebrum (cerebral hemispheres), the optic lobes, 
 the cerebellum, the medulla oblongata, and the pituitary body. All the 
 cranial nerve exits are represented, as well as the internal carotid artery's 
 entry into the pituitary body from below. Two constrictions are con- 
 
 iPhikM. Tram. Roy»l Soc. London, Str. B. vol. 201. 1911. pp. 227-331. "On the structure, development, and 
 morpbolodcal interpretation of the pineal organa and adjacent parts at the brain in the Tuatara (.SpJtnaioa imnc. 
 tabu." by wirthur Dandy. 
 
 Is 
 
52 
 
 MpiriK.iis. ,,1,,. hchiiul the (crcljiuin tin- .ithi-r «.r.......«;. „ .i i .. 
 
 nii.l oj.tip lol.... fro,,, thf „...,lulla ' ""•' '^ ^'"' '■'*'•'•'•'■"">" 
 
 /A'.A-..\7 
 
 «•// /A„V.. 
 
 /m 
 
 .-."r'f loutlorar^H-'';^ "' '^''■"""t"*"'™'' (P=.n..ypo. Cat. X„. 2m): i 
 
l.ack, l)ut >li|iliil.v l(\>.i- ill .l.viiiiiii iluiii tl.. ..nil mil. to ili. ..i. I.rlluni 
 IxyriKl wlii.li it litis a rii|ii<l ili >«■< nt to tli.' f. liniiiii in (ii;i:iii. '| lir inf, Hi r 
 mitlini- ii.-r. ii.l.s KiiKliiiilly fidii tlif fl( < r . f tli." ftiniiiuii ii iinnuin t„ tin- 
 forwnr.lly plac.d pitiiitaiy Imdy wliicli .I.imikIs in liiif uitli llir pust.iior 
 part of til.' cirrlinim. The lower outline of the olfaclorv loi.cs is liori/oiital 
 in advanic of the l.ackwardly ascciidiim lower siiifaee of the eerehriini. 
 
 \iewirn£ the cast from al.ove or lielow the jtreafest l.reailtii i- aiTo«s 
 the cerehrmn in ^reat eoiitrast to the eomparativelv slender olfaetorv 
 lobes, and tiie less slendi'r hut narrow portion extendiii(j l.ark from the 
 eerebrum. 
 
 The brain of Eilniontomiiim. relyinjj on the proportions of the ea«t 
 of the brain-cavity, was about two .iiid a half times as loii^ as its maxiimim 
 height, I.e., from the lower end of the pituitary bodv to the level of the 
 upper surface of the cerei)riini (cerebral hemispheris). For a little over 
 half its length forward from the foramen niatiiiuni it is narrow, aiujiilated 
 above, and constricted on the sides over a coiisideraiile area above the 
 au<litory nerve. Forward it broadens jjnatlv into the cerebrum and 
 ends narrowly in the olfactory lobes. Th<' cerebellum ri-inn with a steep 
 posterior slope, is laterally compressed, but (hies not reach as ureat an 
 elevation as the cerebrum which is the hi^diest part, of the brain. 'I'he 
 anjiulation of the upper surface continues forward from the cerebellum 
 and ends at a constriction deti'iinjt the iiiiider limit of the cerebrum. V 
 lateral angulation run.s obliijuely downward ami forward from the ci le- 
 bellum to above the trigeminal nerve appareiitiv marking the posterior 
 boundary of the optic lobe. The constriction just mentioned (posterior 
 commissure) is continued down the sides in advance of the optic loiie 
 between it and the cerebrum (or behind the jirimarv fore-brain or lha'(im,,i- 
 cephdlon if it were recognizai)le). 
 
 The cerebrum is almost hemispherical in shape, broadly rounded in 
 all directions above, and Hatly convex transverselv in its anterior surface 
 which descends vi'iy rapidly to the olfaetorv lolJes. Laterally where it 
 reaches its greatest breadth ii overhangs its H:ittened lower surface. The 
 infundibiilum extends downward in line with the posterior part of the 
 cerebrum (from the primary fore-lirain) narrowing below with a backward 
 inclination and terminating in the j)ituitary Ixjdy. 
 
 The olfactory lobes, not distinguishable as a pair in the east, are 
 produced horizontally forward an<l are together much broader than deep; 
 they are transversely .'(omewhat concave aliove and moderately convex 
 '.-elow with a slight median, hmgittidinal angularity. 
 
 The medulla occupies about half the inferior lengtli of the brain, 
 and posteriorly is considerably higher tlian broad, angulated both above 
 and below, with its greatest diamt>tcr at about midheight. Farther for- 
 ward it.s sides are sunken, where the walls of the brain-case are thickened 
 in the neighbourhood of the eighth nerve, and its lower surface becomes 
 flattened, retaining, however, a slight transverse convexity. 
 
 Mcasuraneiils uf Cant of Urain-ciwily of Kiliiiontmniini.-< iiHinilijiH-, Cat. .\o. ^.;m). 
 
 Length, posterior end of floor of foramen magnum to terminal ion of optic lobes. 2>'2 
 
 Broauth across cerebrum ~ •" 
 
 Anterior height of olfactorj- lobes Jr. 
 
 Anterior breadth of olfaclorj- lobes ,j'' 
 
 Height vertically uIkivc lower end of piiuilarv ImhIv j,'. 
 
 ■fi 
 
M 
 
 HetRht in linp with trigeminal nerve (V) 7. 
 
 Hroadth at triKrniinal niTve IJ 
 
 Hrea<lthjii«t bchiiiil thpfiidul nerve (Vil) ?? 
 
 HeiBhl in lino with aiiditorv nerve (VIII; 'i^ 
 
 ntvadth behind auditory nerve. ... v] 
 
 Poetcmr height, from lower .urfaco of ine.lulia; in ' a.lvan<e „f hyiH-gLx,,,! nerve 
 
 Poeterior breadth at niidheight of mediilla ....'....'.'.'.'.'.'.'.'.'..'.", 4? 
 
 Teeth. 
 
 ♦hJirf^ ^ ,''^'«^^the manner in which the t.oth follow each 
 
 ., ln» Hadro.saur.diB as a Rroup. Tho numlx-r of vertical series in 
 
 the dentary and maxi lar>- magazines varies in the different irenerin forms 
 
 as al.-^o do.>» ^0 number 01 individual teeth in the vertical seriivs. The 
 
 ^^ iii/r#jiirifvi 
 
 k. gtkMM M mMMMmimM 
 
 wo.n down by u.f crS=?e^'^£^^^^^^^ 
 
 large number of teeth in each jaw and their manner of implantation render 
 the dentition remarkably complicated. As the teeth were evidently worn 
 down rapidly a system of continuous replacement was necessary and for 
 this purpose many reserve or auccessional teeth were provided in vertical 
 senes of from five to eight teeth, each tooth in a serL ovSappbg the 
 one which preceded it. The vertical serits curved outward in the hmer 
 
so 
 
 ftS 
 
 jaw and inward in the upper ono so that thi- worn Hurtiici- <if tht^ t.fth 
 in the two jsiwg rame toKcthcr with a MhcarinK action in an alnioHt vi-rtii-al 
 direction. As a result of the curve in the vertical series, and of the over- 
 lappinn of individual teeth therein, as many as thre;- or even four teeth 
 belonging to a series might he in use ui the siime time, viz., one worn liown 
 to a stump, and one, two, and sometimes tliree succeeding teeth in pro- 
 gressive stages of wear, providing a tesscllnted shearing surface of con- 
 siderable breadth and having a length equal to that of the magazine. 
 The dentary teeth succeed each other in both jaws from the inner side. 
 In the dentary the enamelled face of the crown of the teeth is on the inside 
 providing a continuous enamelhd surface to the full extent of the maga- 
 zine. The maxillary teeth bear enamel on their oiiti-r side and for this 
 n-ason and in consequence of their inward lurve the enamelled surfaces 
 m the vertical series of teeth are not brought into juxtaposition after the 
 manner of the mandibular teeth. 
 
 The teeth of Edmontomnrun conform to the general rules governing 
 tooth implantation and succession in the Hadrosauriihe and are arranged 
 in the usual closely fitting vertical rows of which there are fortv-eight or 
 forty-nine in the dentary with four or five teeth and sometimes the stump 
 of a sixth in each row. 
 
 The dentary teeth are largest at the mid- 
 length of the magazine and decrease in size 
 toward either end of it, the posterior ones 
 being considerably shorter but only slightly 
 narrower than those in front. The inner 
 enamelled tooth-surfaces, in lateral aspect, 
 arc nearly lozenge-shaped in outline, with 
 the longer diameter vertical, and fit closely 
 together (piineunciaUy in a mosaic which is 
 almost half covered from behtw by the thin 
 alveolar wall. The enamelled portion of tin- 
 teeth is evenly rounded above, and eniar- 
 ginated at the narrow base wlure the apex 
 of the next succeeding tooth closely fits. 
 It bears a high, broad-ba.sed, sharp-edged, 
 median keel running its length, between 
 which and the margin on either side, the 
 surface is evenly concave transversely. The 
 succession of keeled teeth from below results 
 in the whole of the inner face of the dentary 
 magazine being regularly fluted in a ver- 
 tical direction. A slight elevation of the 
 margin is developed in the apical curve of the larger teeth, and is also 
 present, to a varying extent, in the smaller anterior and posterior ones 
 along the sides. In the majority of the dentary teeth the margins are 
 smooth, but in the first five or six vertical rows marginal papulations 
 occur between the tooth's apex and the angulation at its maximum breadth. 
 Three dentary teeth, of the same vertical series, in progressive stages 
 of wear, are in use in the cutting surface at the same time. This nur \ ^r 
 toward either end of the magazine is generally reduced to two. 
 
 FiKurc29. Knatnelled face of teetli, 
 in twenty-ninth tn thirty-first vertiral 
 series from the front, in left dentarj- 
 of EiliiH.ntnsaurug, l"at. No 2289; na- 
 tural .lize. 
 
Ill the niHxillary iiiuKiuim< tb.n- jiiv fr.mi Hftv-oiic to Jiftv-tlim- 
 viTfiral riixv. Mf »,.,.|h. Til.- .■i.am.ll..,l f«..,. „f tlir... t.-.tl. i. nirn.w.T 
 than that .,f It... drntary. tl... ni<>ili.<n kr.l i.< hiuli.r in t\w upp. r ,,r lm-.al 
 IH.rtiun of thr tooth, fh." inarKins towanl ih.- ai^x ar.' iiiorr . I.val...| 
 aii.l, 111 til.' sniaJI-r L.th at .itlMT .rKJ. arr .r".,.,! in „„ uhliqu.- .lir.'.-lion 
 l.y niim.Toiis papillus.- ndn,-^. The out. r • naiii.'II.MJ f ,, .m ,,f th.- t.Mtli 
 .1.) not .oml.in.. as on th.- inner .i.l.- of ih,. .I.ntarv ni uazin.- to form a 
 i-ontinuo.is Hut.-,l surfa.v hut pr.-s.i.i a lath.r irr.Kular, loiiKitu.linal 
 row ol .Tovviin in whi.h tin- I.sh protru.l.nt or iion-fun.-ti..ninK l.-.th ar.' 
 M-.'ii, wh.-n- th.. roots of th.- us,.,l up t.-.-th haw .Irofip..! out, .{.■.p-sH 
 l).-t\v.-.n th.. fun.ti..ninK oiu.s. Tlu- n, .xillarv t..th scin to liav- l...,.n 
 
 111 th.- .•uttiiiK ..urfac.-, in a sin^i, , loi.Kitu.liinl r..w in six s.siv.- s,,,,,.., s 
 
 of 1 hr. .- ,sho-.vinu a pr.))ir.-sMv.- amount of H,,,r. It \s |M.,ssih|... h.'w.v.r 
 thU - . -..vi.liia s of this K.-nu-s, two niaxillarv t.'.^lh of th.- sam.^ v.rtica! 
 ^•'' ' . "iivf •"■••n in tin- cuttiiiK surfa.-i- n.-ar lli. mi.l-' nirth .,f th.- 
 
 i-i i IH' at til.- .sani.- tim.'. 
 
 i h.' .-uttiiiK surfa.f uf tlK- il.-ntar'. manazin.- of t.-.tli nut that of th.- 
 !.... illary nuiKazin.- in a sh.arinK a<-tion aft.r th. maniur of th.- Ma.l.-s 
 ' issors. la niaii> jaws of lia.ir.isaurs th.-.s.- .'uttin^ t.x.tli surfa.-.-s 
 :...- h,.t, in an c-v.n pl.m.. l.mKilu.iinally hut an- m.,r.- ..r 1.-^ un.lulatorv 
 a. th.. result of un..,ual w.-ar .)f imlivLlual t.-.-th. For th. sani.- ri-a«on 
 an ur..>v.'iin.-ss of th.; surfarc in a transv.-rs.- din-ction w;is frequent Th.- 
 efT.-.-tiv..n. ss of th.- jaws as shears was ,lepen<l.-nt on the .v.-nrK-ss of th,. 
 .-uttiiiK >urfa.-e of th.- .I.ntal magazines ami the fr..(,u..nf ...•.•urnn... 
 of nn-uular eurvatur.. in th.s.. e.unpo.sit.. .l.ntal surfae.- .-an h.- taken 
 
 ""'>■ ;'^ •■VKl''"' f th.. iiu.tliei..n.-y of this parti.-ular k.n.l .,f .l.ntiti..n 
 
 .-x.'.pl for eutting and ehopping th.- softest ami m.)st sueeul.iit of plmts 
 
 Mni.-<„i;„Hiil.i of Tilth (>/ Kilmiiiilii-tininis, <\tt. Su, 
 
 Tiilh nf right iliiitnri/: 
 
 N()ii-fuiicti.)niii({ todili 
 iiiiinazine - 
 
 H.-itslit .)f inner .'nalnilli'il Miirt:i(i' 
 Muxiniuin hria.lth nf - mif ;ii uw 
 I'.r.'Uilth at lower cikI hi smie 
 \iin-funclioniiiK t(«iili fmni maiiiiIi verli. 
 Hei({lit of enanielle,! viirl;,ce 
 Hre:i{|lli of ntwir ,ii iiiiillii^iifht 
 Uriuillh of same .11 lower .ml 
 Ncm-funilioninK tootli from ^evenlli 
 lleittlil of cnamelltHl siufa.-e 
 Hreaillli of same at miilli.'JKlit . . 
 Hri'aiilh of sami- al Iowit pn.l. . . 
 
 of aviraue .-ize of tli.w iie.ir ili.. rm.llenKlli of tin 
 
 I -niilli 
 
 il row fri m lli.' front 
 
 v.TliiMl ri.w Irom tli.' hack - 
 
 ilh of lift niaxilliiri/: 
 FanctioninK t.«.'tli in twonlv-foartli v.rti.al row fr, mi the fr.mt — 
 
 HciKht of outer enamellnl surface 
 
 Ureailth of sain.' at midh.'ixht 
 
 Hrea<ltli of same at upper (l)a.«al) enii 
 I unclionuiK tooth ia fiflli vi-rtieal row from the front - 
 
 Height of enamelled surface, about 
 
 Breadth of same at midheiKht 
 
 FunctioninK tooth in ninth vertical row from the buck- 
 
 Height of enamellci surface, about 
 
 Breadth nf same nf midheight 
 
 Mm, 
 
 II' 
 .i 
 
 21, 
 111 
 
 HI 
 •I 
 4 
 
 7 
 
 17 
 
 17 
 
 7 
 
57 
 
 v»:HTi>:HH.t:. 
 
 TIhti' (in- Hviiiliihic for prfwiif i|i'Mrii)li.iii mw irrvical itixl tliic< 
 • liirNil ' it.hra' l).|ui.ginK to th.- IIMO -krlctr.ti, (hi. No. ^-iH'.t. Iti l.otti 
 "krl.t... 4 th." ({nal«r |mrf of ih.' tail i:. mi..>in(j, in ilu- tvp.' from l>.'|,ii,i| 
 th.' Mxlh lau.lal, in tlif paraty|M' fropi li<'liin<l tlw fifth," l>iit in inc li tli«' 
 riinaniilfr of the vcrlfl.ral tolunin is* appanntlv prcsmf. I'ntil the 
 .•ni|o.in« nnitrix is r.mov.<l tlir vcrlrl.ral .oiuninax a wiiol.- .annot !,.• 
 i|i'>rnl..(i in .jituii, but till' four v«rtil>ra- of tlir paratvpc .-.. far laki-n 
 from liif loik siipidy witli arrurary the cln'rattiristics of tin- majority of 
 t If piv-afial vrrtil.ra-. ami imli.atr flu- rliannis in form an<l piop,,rtiofi 
 that took phi<c ill pasxinu l.ai k from thi' hijnl. 
 
 'I'hcrc was ti unicral imnasf in .siz,. in t he piivHiicrul vrrt<')>nr in passinu 
 l>a<'k in the scries. 
 
 Thi- (('rvicais, ami the antrrior dorsals at least, were >tronKlv opisthi,- 
 ea-lmis. Neural spines were ah-eiit, or feehly flevelopeil in thi- majority 
 of the eer\ iials until apfjarently late in the series. In the <lursals tliev were 
 short anteriorly in the series but Kaineil slinhtly in length postt-riorly. 
 Ihe transverse proeesses in the anterior dorsals were lotiK ami >toiit, aiid 
 ixniited upward with an inclination outward and forward. In the ixistcrii.r 
 <h>rsals they wire almost horizontal, and less robu.st. The <crvi- d and 
 dorsal ribs with the exception 
 three, were double headi'il. 
 
 if the la*t dorsal, or piwsibly the last vo or 
 
 FiKun>3ll. Corvinil vi>rlel.r!i 
 
 (at. Xo. 2:S9; i niilural i-ij. 
 
 Irririr vii'w. m-. neuml .•aiml; n», m>uriil spine 
 H, ril>; (p, tranK.crst* propesj); «. pn'iyitapoph 
 popliyHi.'i. 
 
 ■(panilyi).' «( KdiuonLi-iuruii, 
 
 A. led lah'nil vii'w; H p<w 
 
 piir:ip.ipyli«ix 
 
 ; / , p<>!iizyKu- 
 
 Cerricdl Virlchni. This 
 vertebra (Figure ;i()j from 
 the paratype of EdwmiUi- 
 muriix is apparently from 
 near the miiKlle of the 
 cervical series. The cen- 
 trum is deeply cupped 
 behind, and the anterior 
 end is t'lrrrcspondinply 
 convex. It narrows to the 
 front, and lias a length 
 considerably in exress of 
 the posterior height aiwl 
 , . , „,, , , . l)readth which latter are 
 
 about Ptiual. 1 he ventral surface i- .arrow and Hat. and .'.nKulated latendly 
 whert> It pa.s.ses into thr- excav:ite,i si.les „f • he centrum. The anterior fac is 
 bounded posterioriy by a definite jirotrudinj; girdle aifiiinst which the 
 narrow rim of the concave posterior . nd of the preceding centrum fitted 
 llie neural arch is lower than hru.ul enclosing a large neural canal The 
 transverse process is short and stout and is directed obliciuelv upward and 
 outw-ard horizontally in line with the neural canal; it terminates distallv 
 in a facet for the attachment of the tubercle of the rib, and gives ofT siiiMr- 
 loriy a short prezygapophysis. Laterally a short parapophvsis with a 
 narrow vertical diameter provides for the attachment of the head of the 
 rib eonsiderablv l)elow the level of the floor ol the neural can.-ii The 
 posterior zygapophyses are long, robust, ami curve backward far b.von.l 
 the post, nor end of tlie centrum. The articulating surfaces of the post- 
 and prezvgapophyses facing downward and upward respectively an- 
 
58 
 
 inclined but slightly from the horizontal. There is no neural spine. The 
 neural arch ends in an angulation above from which two ridges diverge 
 backward, one to each postzygapophysis. With this centrum both ribs 
 are preserved to which reference will be made later. 
 
 N 
 
 MeaauremenU of Cervical Vertebra [dUlorleti) i,f I'arnlype of Edmonlotaurta. 
 
 Maximum lonfcth, aboiil ,», 
 
 Maximum height, about feS 
 
 Length of centrum {o'i 
 
 Anterior height of same, about 74 
 
 Posterior height and breadth of same, about 85 
 
 Depth of concavity of posterior end of centrum qa 
 
 Diameter of neural canal 3? 
 
 Anterior Dorsal Vertebra. The dorsal vertebra here described (Figure 
 61) IS from the paratype of Edmontosaurus and is the anterior one of two 
 having much the same size and proportions. It appears to be about the 
 fourth or fifth from the front in the dorsal series. Two ribs, one of which 
 IS well preserved in its entirety (Figure 33), evidently belong, judging from 
 t.heir proportions, to this particular vertebra. 
 
 The centrum of this vertebra is opisthoccelous, but with the concavity 
 and convexity less than in the cervical vertebra above described. It is 
 longer than high, narrows downward, is pinched on the sides, and has a 
 longitudinal keel below between the articulating ends. The neural arch 
 IS high and robust. The neural spine is short and does not rise much above 
 the top of the transverse processes. It is broad in the fore-and-aft direction, 
 inclined backward at an angle of about 4,5 degrees to the horizontal, is 
 thin, and comes to a sharp edge along its anterior slope the base of which 
 IS vertically above the midlength of the centrum. It extends far beyond 
 the posterior end of the centrum. It narrows slightly above its midheight 
 but regains Its lower breadth by expanding above at the curved superior 
 border which is thickened and rugose. The transverse processes are long 
 and heavy, and rise upward at an angle of about 35 degrees to the vertical 
 inclining backward nearly as much as the neural spine. Anteriorly they 
 come to a thin, sharp edge which is a continuation upward, with a change 
 of direction outward of the narrow upper border of the prezygapophyses 
 Interno-posteriorly a thin flange is developed connecting them with the 
 postzygapophyscs. Externo-posteriorly a much stouter flange extends 
 down to the posterior shoulder of the neural arch. Between these flanges 
 a deep excavation leads downward and is separated from the corresponding 
 excavation of the other side by a median lamella of bone extending up from 
 the neural canal and supporting the pair of postzygapophyscs from below. 
 
 The development of flanges in the transverse processes results in their 
 being subtriangular in outline in cross-section. There is an inner face, 
 broad and flat, an antero-external one becoming transversely concave 
 in Its upper part, and a third directed almost backward also concave with 
 the concavity rapidly increa.sing below. The second and third faces are 
 about equal in extent and both are narrower than the inner face 
 
59 
 
 . ..'^^^ P^^- ^"'^ postzygapophyses, facing in opposite diroctions, are 
 inclined at an angle of about 55 degrees to the horizontal, or about 70 
 
 Figure 31. Anterior dorsal (?fiflh) vertcbniof 
 Edinontosiiurus, C.'nt. No. 2289; i natunil Bi»e, 
 A, left liilcnil aapect; H, iintcrior aspect; C, po»l 
 terior aspect; h, surface for lieiul of rib; bc, neural 
 canal; fia, neural spine: t, surface for tubercle of 
 rib; (p, transverse process: i, prciygapoptivsis: '•, 
 postjygapophysis. 
 
 degrees to each other. Their flat 
 articulating surfaces are oval in 
 outline, with diameters in the 
 proportion of 4 to 7, the shorter 
 diameter being transverse. These 
 surfaces have about the same 
 length as those of the cervical 
 vertebra (Figure 30) but are slight- 
 ly broader. 
 
 The surface for the attiichmont 
 of the head of the ribs is intlicated 
 by a roughness of irregular out- 
 line occurring toward tiie front 
 of the neural arch at about its 
 inidheight. 
 
 The size and proportions of the 
 anterior vertebra supposed to b(> 
 the fifth or si.xth of the series 
 are very similar to the one above 
 described and figured; it is equally 
 well preserved and any si)eciiil 
 referen<'e to it is not considered 
 necessarv. 
 
60 
 
 MeugurriiiriiU nf Dorml Vrrlihiri t. 'fourth or fifth) of i'nriili/iH: of Eihnonlom 
 
 Maxiiiium IcnKth 
 
 Miixiinuin heiKht 
 
 Lnigth of cPDtniTn at mi(lhriK>it 
 
 Anterior lirinlit of centrum, about 
 
 Posterior height of same 
 
 Posterior breadth of same 
 
 IVpth of conoiivity of posterior end of centrum. 
 
 Hcinht of neural canal, about 
 
 Anterior height of neural spine measured along its slope 
 
 Antero-i)osterior breadth of same at upper end 
 
 Transversj? thickness of same at inidlicight 
 
 I^^ngth of transverse proceas measured from biis<' of neural sjiine. 
 
 Mm. 
 
 327 
 
 352 
 
 151 
 
 97 
 
 93 
 
 81 
 
 20 
 
 42 
 
 194 
 
 U)6 
 
 10 
 
 128 
 
 Posterior Dorml Vertebra. The vcrtohra shown in FiRure 32 is a|)par- 
 ently the ast of the dorsal series jutlRinR from the small size of the single- 
 headctl ribs whieh are preserved attached to the transverse processes. 
 Ihis vertebra belongs to the paratype of Edmontosaurus and givea the 
 changes in form that have resulted in passing to the back of the series, 
 r? ^ ^^^ appearance of an interior caudal vertebra which it might 
 readily be mistaken for but for the presence of ribs. In comparison with 
 the anterior dorsals there is an increase in size, the centrum is of a different 
 shape, the neural spine is upright instead of sloping backward, and the 
 transverse processes have become almost horizontal. 
 
 Figure 32. Posterior dorsal vertebra of paratype of Edmontosaurus; 
 • I?*'"™' »'»?• A. left lateral aspect; B, posterior aspect. Lettering 
 as in l igures 30 and 31. i~ "» 
 
 The centrum is about as broad as high, and is very short. The 
 postenor end is moderately concave, the anterior one almost flat with a 
 slight convexity. The sides are deeply concave in a fore-and-aft direction 
 and ventrally a longitudinally directed ridge connects the two ends. In 
 
()1 
 
 poniparison with i\w anterior dorsals the nrurol arch is lower, the neural 
 spine longer, thieker. ami not so hroail antero-posteriorly. 
 
 J he articulating surfaees of the zypapophyses are larfjcr than in flie 
 an erior dorsals the difference heii.R principally in the breadth. Their 
 out ine IS broadly oval, the proportion of breadth to length being about 
 as 4 to i) J hey sloi)e at an angh- of about 20 degrees to the horizontal 
 and are far her apart than those of the anterior dorsals. The anterior 
 border of the neural spine starts narrowlv from between the i)rezvga- 
 pophyses and is continued thinly uimard toabout the nii.lheight of thespine 
 iToni each postzyga|)ophysis a short, stout flange jmiceeds upward to 
 lie neural spme as lateral Ix.undaries to a median excavation whi< h 
 hecoming shalh.wer in its upward cour.se ehannds th<. posterior bonl..r 
 of the neural spine to above its midlcngtli. 
 
 The transverse im.ces.ses are shorter than, and slender in comparis. n 
 with, those of th<' anterior dorsals, an<l lack the latter's conspicuous devel.p- 
 nient of flanges. They proceed directly outward from between the 
 pre- and postzygapophyses with only a slight inclination upward. Their 
 strongest connexion below is with the anterior border of the neural arch 
 in the nature ()f a buttress merging with the prezvgapophv.ses. The 
 outline of their cro.ss-section at midlength is somewhat ovaf with the 
 greater diameter horizontal, more roumled in front than behind, and more 
 than twice as broad as deep. 
 
 M,n.-<,in in, „h <</ l'o.-<l,nor iMis.il V.rl.hrn „/ PamliJiH- of E,lm„iil„m<irm. 
 
 Maximiiiii liciijlit 4n« 
 
 Maximum brciultl. (.lisianc h.-tw.M... „ui.t .iMlsOf tian^vcrs,.',,r.„ess..s;, about 317 
 
 Hroaillli of .same .^-^ 
 
 HoJKlit of same '?.•; 
 
 Amount of coucavily of imsterior end of sainc. 2^ 
 
 HriKht of neural spine above base of transverse proeess o1|. 
 
 Atitero-poslenor breadth of .sanu- at niidheiitlit '-i 
 
 T hirkne.ss of same at midheiKlK .>, 
 
 Hei({lit of neural canal J, 
 
 RIBS. 
 
 The ribs of Edmontosaurxts at present available for description belong 
 to the paratype and consist of the pair in plare on the cervical vertebra 
 above described (Figure 30), the pair preserved with the posterior dorsal 
 also already described (Figure 32), and two, presumablv a pair, apparently 
 belonging to the anterior dorsal vertebra shown in Figure 31. 
 
 Cervical Kihs. The rib.s of the cervical vertebra, Figure 30, are 
 double-headed and very short, and consi.^t mainlv of a triangular plate 
 of bone, diminishing backward, composed of the shaft and the broad 
 tubercle set in a vertical plane. The neck is given off below from the 
 front of and at right angles to the shaft, its junction with the shaft being 
 sharply angulated externally. The neck is broad antero-posteriorly. 
 and thin, thickening internally for the formation of the head. This 
 latter, connecting with the short parapophysis, is much broader antero- 
 postenorly, than deep. The posterior portion of the shaft is short, slender, 
 and triangular in cross-section, being flat above, and keeled below by 
 the bacKward continuation of the angulation at the outer termination of 
 the neck. 
 
 8320-! 
 
62 
 
 Thoracic Ribs. 
 
 t 
 
 Figure 33. Right rib of ?fourth or 
 fifth dorsal vertebra of paratype of 
 EdmoBtoaaunis; anterior view obli- 
 quely from without: J natural siEe. 
 A. head; t, tubercle. 
 
 Of the pair of ribs assigned to the anterior dorsal 
 vertebra (?fourth or fifth) the one of the 
 right side is complete and well preserved, 
 the left one is in an equally good state of 
 preservation but lacks a short piece from the 
 lower end. 
 
 The.se anterior ribs (Figure 33) are long 
 and strongly built with a moderately curved, 
 tapering body or shaft, a well-developed 
 head and tubercle, and a deep, thin neck. 
 In the upper half of the shaft the bone is 
 thick with a rounded border along the antero- 
 internal curve and down to the head; along 
 the postero-external curve and between the 
 tubercle and the head it comes to a rather 
 thin edge. The broadest part of the rib is 
 below the tubercle. The posterior face in the 
 upper half of the shaft, and for a short dis- 
 tance past the tubercle toward the inner 
 border of the neck, is transversely concave. 
 For a corresponding distance on the ante- 
 rior face the surface is transversely convex, 
 the convexity developing down the shaft into 
 a well-defined median ridge which merges 
 farther down into the antero-internal border. 
 It is along this ridge that the bone id thickest. 
 In the lower half of the shaft the bone 
 bceomos more nearly ova« =n cross-section 
 being somewhat thi Her near the outer curve 
 with the greatest diameter directed externo- 
 internally. Along this lower portion of the 
 shaft the rate of taper is lessened. At the 
 extreme lower end the bone thickens and 
 there is a roughened surface for the attach- 
 ment of the costal cartilage. The neck is 
 directed downward, inward, and shghtly for- 
 ward at an angle of about 110 degrees to the 
 upper part of the shaft. 
 
 The head of the rib is set rather squarely 
 across the neck and expands to a thickness 
 which is twice that of the neck near its lower 
 border. Its articular surface is undulating, 
 pitted, and rugose with nn irregular lengthened 
 oval outline about twice as deep as broad. 
 
 The tubercle is prominent but much 
 smaller than the liead. Its articular surface 
 is about half that of the head in area and is 
 set at much the same angle. From the point 
 of view at which the rib has been drawn 
 neither of these articulating surfaces is fully 
 seen in Figure 33. 
 
63 
 
 Meaturemenla of Right Thoracic Rib {t/ourlh or fifth) of Paratype of Edmoittoiaurus. 
 
 Length along antero-internal curve from the head to the lower end (about 53i 
 
 inches) ' j gg,, 
 
 Distance from upper end of tubercular facet to top of head. ... ' 18(» 
 
 Depth from top of tubercle to inner curve 140 
 
 Depth of neck at about its midlength 75 
 
 Thickneiw near lower border of same j7 
 
 Height of capitular facet 74 
 
 Breadth of same 35 
 
 Height of tubercular facet 45 
 
 Breadth of same 28 
 
 G. jater diameter of lower extremity 4j 
 
 I<es8er diameter of same 04 
 
 Greater diameter jf rib at midlength 42 
 
 Lesser diameter at midlength ..............[].'. 21 
 
 The ribs attached to the large posterior dorsal vertebra (Figure 32) 
 are very short with a length of only about 85 mm. They decrease in 
 diameter rapidly for one-third of their length outward from the transverse 
 process and then retain much the same size for the remainder of their 
 length. They are vertically compressed with the greater diameter equal 
 to about twice the lesser one. They incline a little forward and have the 
 upper surface directed slightly to the front. 
 
 Fore Limb. 
 
 Humerus. The humerus of Edmontosaunts is a robust bone slightly 
 over four times as long as its upper transverse breadth. The radial 
 crest is very strongly developed and is the most conspicuous feature 
 of the bone givmg to it in its upper half the great breadth common to the 
 humeri of the Hadrosaurida;. 
 
 In the right humerus, Figure 34, of the paratype of Edmontosaurns, 
 the shaft is somewhat sigmoid in its length bending backward in its upper 
 half and to about the same extent forward below. The head is rather 
 small and occupies a central posterior position superiorly overhanging 
 the shaft. It is supported beneath by a strong buttress, with a rounded 
 border, passing below into the posterior face of the shaft. It is roughened 
 on the upper and hinder portions of its convexity, is deeper than broad, 
 and forms the highest part of the upper surface <■ the bone. The inner 
 and outer tu jcrosities extend outward on eithc: de of, and at a lower 
 level than, the head with a forward curvature w. h renders the anterior 
 face of the bone above concave. Of the two tubtio.^ities the internal one 
 is the stouter. The radial crest extends downward on the shaft from the 
 outer tuberosity as a comparatively thin flange to below the midheight 
 of the bone. It keeps about the same breadth downward before it suddenly 
 naiTows and becoming increasingly thicker merges into the shaft. From 
 the inner tuberosity an obtusely angulated ridge extends down the shaft 
 with decreasing prominence to below the level of the radial crest. The 
 shaft below the radial crest is thick and strong with a somewhat ovate 
 oi'tline in cross-section, the greatest thickness being anterior and slightly 
 external. The lower extremity narrows slightly backward and is flattened 
 on the sides. The condyles arc well rounded below, narrow tranaverselv 
 
 832*-SJ "' 
 
 i 
 
 .b 
 
64 
 
 nn<l protrudent in front. The inner one is the larger of the two and thicker 
 both in front and l)ehind. Its forc-and-iift ciiamctcr is equal to the maximum 
 combined condylar breadth. The condyles are separated below by a 
 deep uroove which behind continues up between them to the shaft and 
 in front widens into a large concavity. Posteriorly on the shaft, toward 
 the inner side, at about one-third of the bone's length from the top, there 
 
 otb (; 
 
 Figure 34. Right humerus of paratype of Edmontosauiua; \ natural siie. A, anterior aspect; 
 B, posterior aspect; C, outline of proximal end; D, outline of distal end; ant, anterior; A, bead; itii; 
 inner tuberosity; oc, outer condyle; otb, outer tuberosity; re, radial (deltoid) crest. 
 
 is a prominent, roughened, vertical ridge for muscular attachment. Also 
 the lateral surfaces of the distal end of the bone, and the border, and 
 external face, of the radial crest in its lower part are coarsely striated for 
 muscles. As the radial crest is directed obliquely outward and forward 
 it is foreshortened when viewed as in Figure 34, A and B, and appears 
 narrower than it really is. 
 
65 
 
 MeanurrmenU of H'ght Humerun of Eiimonbymuriu, Cat. Xo. J489. 
 
 Mm. 
 
 U-nrX\\ (104 
 
 Maximum trstrnvtrw brrailth at |ir<>ximal pnd 1(17 
 
 Dutance fniiii liiwcr angulation of radial cri-Ht to poHtcrior fat-c of nhafl I»tt 
 
 ThirkncHU of railiul crcHt at ilH iiiidli-nKtli anti breadth 21 
 
 ThickncHM of Hamc at a Hhort liititant'c in from its Iowit anKulation :i(( 
 
 AntiTo-poHterior <liameter of Hhaft at onc-tliinl of the Jxinf's Icnftth from dintal 
 
 end 1(2 
 
 Interno-«'Xti'rnnl diameter at name level 70 
 
 Maximum tranHVerNc breadth of dixtal end I Iti 
 
 .\iitero-|HiMterior diameter of inner condyle 114 
 
 Anlero-|io«terior diameter of outer condyle KM 
 
 Jta 
 
 Ulna (U.). Figure 35. The ulna is tlie 
 longest bone of the fore limb, the humerus 
 being the next in length, with the radius slightly 
 shorter than the humerus. The ulna exceeds 
 the radius in length by about 95 mm. It is 
 slender for its length, is heaviest in its upper 
 half, and reaches its maximum size proximaily. 
 Distally it is only slightly enlarged. At its 
 upper end its outline in cross-section is trian- 
 gular. Here the olecranon process is well deve- 
 loped rising to a considerable height above the 
 articular surface for the humerus, .\nteriorly 
 toward the inner side above it is excavated 
 for the proximal end of the radius, the exca- 
 vation narrowing and lessening downward, and 
 ilisappearing above the bone's half-length. 
 Below the olecranon process posteriorly there 
 is a protrudent angulation which accentuates 
 the general forward bend of the bone in its 
 upper part. At midheight the shaft is oval in 
 cross-section, with the greater diameter fore- 
 and-aft, and one and a half times the lesser 
 diameter. Distally the greatest diameter is 
 nearly twice the maximum transverse breadth, 
 and on the inner side toward the front there 
 is a rugosely striated, depressed surface for the 
 close application of the distal end of the radius. 
 Throughout, the lower end of the ulna is deeply 
 striated in a longitudinal direction for the inser- 
 tion of muscles. 
 
 Mniiiiirnii) rils iif hft I 'tiiii of I'aralj/iH' of Kilmonloxniirun. 
 
 .Mm. 
 
 L<'nRth 76() 
 
 Maximum transverse brea<lth of proximal end 128 
 
 Maximum diiinieter of distal end 114 
 
 Maximum diameter at midlength 80 
 
 D J- /D \ mu J- Ti- n- ■ Figure 38. Left ulna and radius 
 
 IfmtU-O l.nO.). Ine radms, Figure 35, is of paratyne of Kdmontnsiarug; 
 
 slender, nearly straight, and shorter than the *,. f?',"'?' *'**=. ""erior view 
 ulna, with a length equal to about 6§ times its n^i^T^"^L-'i"MZ 
 
66 
 
 maximum thickness proximally. Both ends are enlarged, the proximal one 
 more than the distal one. In comparison with the ulna, the radius is 
 more slender throughout, with less disparity in the size of the ends. At 
 midheight the shaft has an elliptical outline in cross-section as in the 
 ulna but smaller, the diameters in the two bones being in about the pro- 
 portion of 4 to 5. The outline of the proximal end in superior aspect 
 is nearly square with the greater diameter transverse and the outer and 
 posterior sides fitting into the angular excavation of the ulna. The increase 
 in the size of the proximal end is rapiH on the inner and hinder faces, par- 
 ticularly on the latter. Externo-anteriorly for some distance below the 
 upper end the bone narrows outwardly forming a vertical ridge, most 
 protrudent above, which is rugosely striated in the direction of its length 
 und is in close contact, when the bone is in position, with the ulna. The 
 lower end is angulated internally and thickens toward the outer side where 
 it is applied to the ulna. On all sides it is longitudinally striated deeply 
 for muscular attachment. Similar striations are conspicuous also at the 
 upper end. 
 
 Mrnsuriinruts of Lr/l RivUhk of Paratype of Edtnontotaurus. 
 
 Mm. 
 
 Length ''63 
 
 Muxiinuin transverso brcwlth of proxinwl end 98 
 
 MaxiinuDi diameter of dixtal end 87 
 
 Maximum diameter at midlenKth 63 
 
 THE GENUS EDMONTOSAURUS. 
 
 The orthopod genus Edmontosaurus of the family Hadrosauridx, 
 subfamily Hadrosaurina (p. 68) represented by the single species A'. 
 regalia, Lambe, has the following characters : 
 
 Generic and Specific Characters. Skull moderately elongate, higi; and 
 broad posteriorly, flat in the frontal region, laterally compressed behind 
 a low, greatly expanded snout. Orbit large. A large pocket-like recess 
 developed within the postfrontal, leading from the orbit. Lateral tem- 
 poral fossa restricted above. Palatine and pterygoid rising, at a high 
 angle, inward. Ectopterj'goid external to the maxillary and pterygoid, 
 connecting the two. Mandible deep and strong, very slightly decurvod 
 in front. Teeth with a rounded apical outline in lateral aspect, keeled, 
 and with smooth borders; in 48-49 vertical rows in tli*; dentary, and 51-53 
 in the maxillarj-. Ischium long, bluntly pointed distally. Femur slightly 
 longer than the tibia. Humerus nearly as long as the ulna. Cervical 
 and dorsal vertebrae opisthocoelous, in a marked degree in the former. 
 Dorsal spines of moderate size, increasing slightly in height backward in 
 the series. Sacrum composed of eight vertebrae. Animal of robtist build, 
 between 30 and 40 feet long. 
 
 Edmontosaurus approaches mos^ 
 geological age, one of the principal ch^ 
 found in the general shape of the skull 
 in Didonius greatly depressed. The 
 
 reserved for D. mirabilis, Cope, from the Lance formation of Dakota, 
 sometimes referred to as Trachodon mirabilis a genus and species insecurely 
 established by Leidy in 1856, on the tooth from the Judith River beds of 
 
 "losely Dicloniiis ("ope of later 
 
 ters distinguishing the two being 
 
 . ich in Edmontosaurus is high and 
 
 n.^me Didonius, as used here, is 
 
«7 
 
 Montana. No characters can at present be assiKned to Trachodon lK>yond 
 those derived from the single mandibular tooth which constitutes the 
 type.' 
 
 Edmontosaurua rivalled in size its bulky contemporary HypacrosnuruB. 
 It appears, however, not to have been as large as Prosaurolophus, from the 
 Belly Hiver formation of Alberta, if the skull in the Hadrosauridie can be 
 considered a criterion of the she of the animal as a whole. 
 
 CLASSIFICATION OF THE HADROSAURID/E. 
 
 DIVISION INTO THREIi: St'BKAMII.IKS. 
 
 The discovery in reci-nt years of many new generic forms of Hadro- 
 saurido; in the western Cretaceous of this continent, more especially in 
 the Bi'lly River and Edmonton formations of Alberta, has greatly enlarged 
 the list of known genera of these herbivorous dinosaurs, and has been the 
 means of increasing our knowledge of their osteology. As a result of the 
 study of these forms it is apparent that three principal groups or sub- 
 families are represented. 
 
 In 1914' a classification of the Hadrosauridie (Trachodontida;) was 
 proposed by Mr. Barnum Brown who recognized two subfamilies, viz., 
 the TrachodontincB and the Saurolophince. Since then, principally through 
 the discovery (1915) and further study of Cheneosaurus, the discovery in 
 1917 of a nearly perfect skull of Stephanosaurus, and the additional study 
 of the family as a whole, greatly assisted by the well-preserved specimens 
 in the collections of the Geological Survey, it has become evident that 
 certain forms included in the SaurolophincB differ from the Saurolophua 
 type in so many fundamental particulars that their withdrawal to form 
 a new subfamily is necessary. For this third subfamily of the Hadro- 
 sauridie the name Stephanoaaurince is proposed, to include the genera 
 Stephanosaurus Lambe, Corythosaurus Brown, Cheneosaurus Lambe, and 
 probably Hypacrosaurus Brown. Under the proposed new classification 
 the SaurolophinfB are represented by Prosaurolophus Brown, and Saurolo- 
 phua Brown. The Hadroaaurinm {TrachodontincB Brown) embrace Grypo- 
 saurus Lambe, Kritosaurus Brown, Edmontosaurus Lambe, "Claosaurua" 
 Marsh, and Diclonius Cope. 
 
 The characters denoting the resemblances and dissimilarities of the 
 three subfamilies, as provided principally by the skull, are as follows: 
 
 '"On the lenua Trachodon of T«idy," by L. M. Lambe, Ottawa Naturaliat, vol. XXXI, No. 11, February. 
 1918. 
 
 ■Boll. Am. Mm. Nat. Hist., New York, U.S.A., vol. XXXni, art. XXXV. 
 
 ¥. 
 
yr ■■- ■ 
 
 68 
 
 
 
 lladromuridit. 
 
 
 1 
 Subfamily 
 
 Subfamily 
 
 ( 
 Subfiunily 
 
 Haihiuaurina 
 
 Saurnlnphinit 
 
 .StrphaiuuMiurintr 
 
 FuniM Iwicc 
 
 KonuH liirni". 
 
 KoriiiK of vai iable »iie. 
 
 Portfriiir hciRht "f skull 
 
 vuriiibli". 
 Hu|)rnortiitHl nwo" Hat. 
 
 Skull hiith iMwirriorly. 
 
 Sk\ill hiKti: relatively »hort. 
 
 Supraorbital i-rcat ilcvi'l<i|»- 
 
 Siipraiirliiliil renion elevattnl 
 
 
 i'<l. 
 
 into hiHMl, or ilome 
 
 FnMito-imrii'tul an-a i-ii- 
 
 UrKc<l. 
 Nawili* I'xtcinlinK far fiin^'iiril 
 
 l-'ronto-iNirii'tal area imxler- 
 
 Fninlo- iwrietal area iclui-- 
 
 atclv larK<'. 
 
 cl. 
 
 NiiMaln t'Xti'mtinK far for- 
 
 NaitaU re<'e<le<l. 
 
 Anterior iianii IranNViTwIy 
 
 waro. 
 Anterior iian-n tranitverxely 
 
 .Vnterior nani< wparuli'd \)\ 
 
 cuiiflueiil. 
 
 _ eonfluent . 
 
 pr<>tiiaxillarH'M. 
 
 Naiial iiawutRCM anteriorly 
 
 Nasal itawaiceH anteriorly 
 
 NaHal piuooiKi-H eneloxed by 
 
 not pni'loxnl ill bonr. 
 
 not enckiwti in Ihuii*. 
 
 premaxiUarieK, ami ureiiily 
 enlarKi<<l in nupraorbitul 
 
 Preniuxillariett cdiiKneii to an 
 
 I>remaxillarie!i eonflned to 
 
 rejjion. 
 I'remaxillarieH prolonKol 
 
 anti-rior poitition. 
 
 an anterior ixMition. 
 
 backward and enterinK 
 loTKely into fomiatHui of 
 h<i<Ml or dome. 
 
 Lachrymal of mo<lt'rali> alic. 
 
 I>a(-hr>'inal larp-. 
 
 Lai'hryiiial re<lue<>d. 
 
 lachiuin pointc)! liiNtally. 
 
 iHehituii i'xpan(le<i distally. 
 
 iHi'bium eximnded diatally. 
 
 OwM-ra: 
 
 (ienera; 
 
 Genera : 
 
 Gryposaurus. lidly Rivrr 
 fnnnaliun, 
 
 I'roKaiirolitphufi. Belly 
 
 Slrphitruunuruo. R'lly 
 lliver formation. 
 
 lliver formation. 
 
 A'rtluraurux. Oio Alamo 
 b«l8 of Now Mexiro - 
 
 f Kfimnntitn fikrnintinn 
 
 Saurnlophm. Kdmonton 
 
 ('DrythoHiinrun. Belly ltiv<'r 
 
 format ion. 
 
 formation. 
 
 EdmoiUomurus. txlmonton 
 formation. 
 
 ''('laomuTU.^" . I.ianec for- 
 mation. 
 
 IhrUmiim. Lance fonna- 
 tion. 
 
 CheHvoxaurut. Edmonton 
 formation. 
 tUyiMcrnxniiTVK. Kdmon- 
 ton formation. 
 
 From the above comparison of the subfamilies of the Hadrosauricla> 
 it is apparent that the Hadrosaurinw and the Saurolophinfe show a closer 
 approach to each other than to the Stephanosaurinw. These last stand 
 apart with very marked and striking characteri.stics in about an equal 
 degree from both the others. In them there is a supraorbital enlargement 
 of the skull due to the surprisingly great development and backward 
 extension of the premaxillaries and nasals. In the Saurolophince instead 
 of a general superior enlargement of the skull there is a crest over the 
 eyes, formed by the nasals in Prosaurolophus, and, according to Brown, 
 by the nasals, prefrontals, and frontals in Saurolophus. 
 
 The only one of the above listed characters common to the Saurolu- 
 phina and the Stephanosaurinw is the distal expan.'sion of the ischium. 
 It was this "footed" form of ischium, discovered by the writer in 1898, 
 and first described by him in 1902', in connexion with his original description 
 of Trachodon (Stephanosaurwi) marginalun, and not until then known 
 in association with any type of orthopod (predentate) dinosaur, that was 
 considered by Hatcher to belong to "some member of the Theropoda" 
 
 CiMitributiuiu to CaBwiian Paiaoatoloo-, vul. Hi iquftrto;, pt. II. 
 
eo 
 
 as cxpri'swd in his "(it-olony iiixj |mla'<intol()(jfy of ihf Juilitli Kivor Im'iIc." 
 I'JOS, |). 07.' TluM uulhor in the writrr'.^ opinion aim* crnii in Win ri iniirii^*'', 
 uniirr the Kiinic hciiiling in liis r<-|M)rt, on the niatiriiii on which S. mar- 
 giniilus WHS i-ctulihsiieil, hh furthi-r work on thf rich dinoHauriun faunu 
 of the Belly Uiver Im'<1h of AllMrtii Utin no fully proviil. 
 
 Thi' nicnihcrs of the Hadromunnn untl Saurolofthhur resemble each 
 other in havinK an elongated narial vacuity, ofM-ninK thmuKh the •.kuli, 
 enclosed nlwtve hy the nuttalu and premaxillaries. In lM)tli suhfuinilies 
 there it H forward extension of the nat>als, and a limitation of the pre- 
 MiiixillnrifM to an anterior pottition in the Nkull. They differ from eai'h 
 otlier in the absence in the first and the presence in the other (»f a "font" 
 or distal expansion in the ischium. 
 
 Th'- three subfamilies show distinctive characters in the relative 
 size of the parieto-frontal region, and of the lachrymal. j 
 
 The Strphanumurinm are characterized by an extremely h Kh skull 
 in iniirkcd contrast to the relatively low skull of the Uadromn' imr and 
 Suiirolophina, the extreme of skull depression l)eing reached in th'' Hailro- 
 mufiita:, viz., in the genus Dicloniiu. The primary character'^ of the 
 Stephanosaurina separating it from the other two are— (1) the enve'opnient 
 of the anterior nares in, an<l their separation by, the pn*maxillaries< (2) the 
 extreme backward extension of the premaxillaries and their enclosure of 
 tl\e narial passages, (3) the enlargement of each narial pa-ssage posteriorly, 
 within the supraorbital hood or dome, into an extensive air-chamls-r 
 bounch'd by the premaxillaries and nasals. 
 
 In these subfamilies the appendicular skeh'ton and that of the trunk 
 provide also characters which no doubt can be relied on as being distinctive 
 in each. 
 
 The Stephanosaurince were more highly specialized than either the 
 Hndromurinae or the Saurolophinee. The arrangement of the elements 
 enclosing the anterior nares and narial passages implies different habits 
 and may indicate a better adaptation to an aquatic life. 
 
 The earliest meml)er of the Hadronaurince is Gryposaurua from the 
 Helly River formation of Allierta represent ■' in Figure 36A by the skull 
 of <i. notabilig n-markable for its completeness and wonderful state (»f 
 preservation. 
 
 The second genus of this subfamily, viz., KritosauruK, from a not 
 definitely determined geological horizon in New Mexic<» (the Ojo Alamo 
 iM'ds of San Juan county = ?Edmonton formation of Allterta) is note- 
 worthy for the great posterior height of the skull. The radical differences 
 iK'tween GrypoKaunm and Kritomurus, particularly those conspicuously 
 seen in the shape and size of the predentary and the proportionate length 
 of the quadrate, make it probable that further fundamental dissimilarities 
 will be revealed in the skull and other parts of the skeleton when the 
 osteology of Kritosaun. is better known. 
 
 The type of Kritomurus consists in general ti'rms of the hinder half 
 of the cranium, and a complete mandihle, which latter reveals the length 
 of the skull (Figure 36B). The orbital rim, including the po.storbital 
 bar, is, in the mounted skull, mostly restored in plaster, and all the facial 
 
 ■"Cenlocy and palsoiitoloo' ol the Judith River ImmIs". h> T. W Siantoo and J. B Hatrlier. with a chapUT 
 on the fomil plantn^by F. H. Knowlton; Bull. No. 257. I'.S. (;tH>l. Surv. 
 
 •Tittid by (t. F. Rnwon in "Th« strati^flphv of th*> M^-^ntMAA isr.".tfp, with ^^.^..-itij F..(errwv t.> The p.>Hft.* (tml 
 age o( the Judith Hiver formation ia iiarth.ceEtral Moaiaaa", I*rof. Paper 99, t .S. Ueol. .Surv , I9U. 
 
70 
 
 ek'montM in udvuncc of the orhi', with the pxception of the maxiliiiry, 
 hftvp aixii born restored, providimii a rather remurkable na§ul :*nd pre- 
 miixilliiry contour. The nmxillarx appears to be preserved to near it' 
 lower anterior extremity. 
 
 Fisure 36. Skulls o( Hadrosauriiw. A, Gr>-po»auru!«, Lambe; B, Kritoaaurus, Brown, -ft 
 
 Edmontosaurus, " Claosaurus " annectens, and Dicloniiis, Figures 
 37C, D, and E, respectively, the remaining members of the Hadrosaurina, 
 illustrate well the general tendency in the crestless forms to a lowering 
 of the skull as time progressed. 
 
71 
 
 Fif(art! 38F in f a >kull of Promurol^phun -^Mximan Hmwti. dbtiiineil 
 by C. M. SternborK of ihp (Jcologipal .Survey vertcdratr i>ftltp<mtol(>(KicHl 
 party of 1014 from bed-* of tb«' IMlj' llivrr foruwitiun on Red l>«'»-r rivt-r, 
 
 Fiiiuro a7. SkuiU o{ I!a>iroiauriikt]. C, E<lmonu>iauruj, Lambc; I>, "Ctaoaaurus," Mush; 
 £, Diclonius, Cope. -^ natural »ite. 
 
72 
 
 Pmx 
 
 Figure 38. Skulls of Snurolopliinic 1", Prosaun>l(>phui>, Brown; G, Saurolophus. Drowiii 
 iS natural Mie. 
 
H 
 
 J. d^'r^'^^l^L^'t^rirsHL. "• '^'''"""»»"™"- '-"""^ •• ^orytho^u-u.. B«.w„; 
 
2 miles east 'of the mouth of Little Sandhill creek. The specimen consists 
 of all the cranium and mandible in advance of a line passing irregularly 
 down from the front end of the supratemporal fosste, and supplies the shape 
 of the mandible, and the true length of the snout which is apparently 
 restored to too great a length in the genotype described by Brown in 
 1916.' In the Geological Survey skull the premaxiikry and nasal bones 
 arc complete and give the proper extent and manner of union of the nasal 
 anteriorly with the upper limb of the premaxillary, the true outline of the 
 posterior termination of the lower limb of the premaxillary, and the position 
 and shape of the posterior end of the nasals. Both the upper and lower 
 teeth are well preserved. The specimen proves that in Protaurolophua 
 the "crest" is formed entirely from the nasals and not chiefly from the 
 frontals as supposed by Brown. In Figure 38F the posterior end of the 
 skull is restored from Brown's figure of the genotype. The skujl of 
 ProaauTolophua is thus seen to be much shorter than originally described 
 and more in accord with the outline of Saurolophus Brown, from the 
 Edmonton formation. 
 
 A great advance was made in our knowledge of the structure of the 
 skull of Stephanosaurus by the discovery in 1917 in the Belly River forma- 
 tion. Red Deer river, of* a skull of .S'. manjinatus much more complete 
 and better preserved than the one describtvl by the writer in 1914.' In 
 the 1917 specimen (Figure 39H) the extraordinary contour of the head 
 is fully given, and as most of the sutures are traceable, the boundaries 
 of the variou.s elements are revealed, clearing uj) points of doubt as regards 
 the determination of the bones not only in Stephanosaurus l>ut also in 
 Corythosaurvs and Cheneosauruf, other known meml)er8 of the subfamily. 
 
 In the StcphanosauriruB the premaxillaries are greatlv extended and 
 enlarged posterio.iv relegating the nasals to a position surprisingly far back 
 in the skull. 
 
 In Skphanosaurus the top of the skull bears a high hood or crest, 
 narrow from front to back, and laterally compressed, from whose posterior 
 base ther(> is a comparatively slender backward prolongation forniing a 
 process which reaches far beyond the occiput at a considerable distance 
 above tiie level of the parieto-squamosal bar. The crest with its posterior 
 »xtension i.-< made up of the premaxillary and nasal bones. The inferior 
 portion of the premaxillaries is greatly expanded posteriorly to form the 
 central, lower part of the crest proper on either side. Superiorly the 
 premaxillaries form the whole of the cre.st above, rising vertically in front 
 and d<>^<n(ling as steeply behind, thence continuing backward to take 
 part in thv formation of the posterior process. The n.i.xals extend obliquely 
 upward and forward from in advance of the small frontals and appear 
 externally in the crest between the broad hinder termination of the inferior 
 part of the premaxillaries (which cannot properly be referred to as a 
 owed limb of the premaxillary) and the posterior descending portion of 
 the prcniMxillarie.s above. They also extend narrowly backward beyond 
 the frontals as part of the crest prolongation constituting the lower surface 
 of the process, embracing the premaxillaries from below, and more pos- 
 teriorly enveloping them externally also. In the back part of the crest, 
 therefore, and in the crest-prolongation, the premaxillaries are between 
 
 ioull. Am. Urn. Nat. Hiat., vol. XXXV, pp 701 TM. fi«» 1 and 3. 
 Tba OtUwa Nkturalist, vol. XXVHt.pp. 17 W.platel. 
 
75 
 
 the nasals, that is along the whole of the latter's length. A long narrow 
 vacuity in the crest occurs between the nasals and the lower premaxillar^' 
 expansion. ^ c^maij 
 
 ..r^'^^l'"'^' *'*'a"o*.K''««ve runs obliquely upward and slightly backward 
 across the lower portion of the premaxillary a short distance "in advance 
 of the ant«nor end of the jugal. This groove was considered to mark the 
 back termination of the ower part of the premaxillary ("lower limb of 
 the premaxil a") in the oriMnal description of the skull of Stephanoaaurua. 
 What was then named prefrontal is now clHttrlv seen to l.e the ureatlv 
 Mcpanded ix.stero-inferior part of the premasiilarv a^ the structure of the 
 bone IS continuous across the jBroove. The prefrontal is small and assists 
 fr,It I T. "i . '^ *'"*"' "m '"^tween the lachrymal and the post- 
 
 froBta . The sinall frontal is excluded from the orbital rim bv the pre- 
 froBtal and iwstirontal, uwi is well under the anterior, lower surface of 
 the naso-jiwemaxillary proces?;. 
 
 In thf light of our increaH^.1 knowledge of the structure of the skull 
 of St^pi„i:,omuru, the oriffnal description of the skull of < orythomurus 
 ilrowii t-ai, 1 ... amended in .^ertain particulars. What was called prefrontal 
 i iMgur;. .m MS now <-learly i*een to be premaxillary. The l,one above the 
 orbit (leT^riumed b.. Brown as frwit.il is prefrontal. The fronta' is sinall 
 .MS 1,1 St.^iih^,„<m,,.-us ami is hi^Weii beneath the crest. What is named 
 rontal above the pi.stfrontn! and ^|uamo.sal and forming the lower, hinder 
 border ot the crest is na.sal. Tl*^ front part of the crest is not nasal but 
 the prolongation upward of th.^ pr. ji.axiUary. If the sutiirr in the anterior 
 part of the crest in lirown's Hcure of Corythomunis, marking the back 
 termination (jf the nasal (firemaxiJlarji be correct then the whole of the 
 crest above the narrow central vacuity may tm nasal. If this line be not 
 a suture then the premaxillari,.s form the upper part of the crest some- 
 what as in i^U'/jnanomiuriis. 
 
 In the Stfphnnosaurinw the premaxillaries .sei)arate the extern.'d nares 
 and nasal pa.ssages, the laHer being enclosed outwardlv bv an upward 
 growth ot the floor of the passage and a downward bend of the roof of 
 the same. 
 
 In Slephnnomunis the nasal pas.sages lead up into the front part of 
 a large double chamber within the crest, the entry being made at about 
 the mulhnght of the chamber on either si.le of a vertical median .septum 
 J his nasal chamijer occui)ies the greater part of the crest within, is Hanked 
 outwardly by the premaxillary and nasal bones an.l is somewhat over 
 l.KJ mm in lieight, and narrow from side fo side, with a fore-;ind-aft diameter 
 about threc-hfthd the height. \n exit from the chamber is present below 
 posteriorly leading downward. The jv.sition of the chamber is indicated 
 externally by the greater convexity of the crest laterallv in an area sur- 
 rounding the narrow central vacuity. The Stephanosaunnid form of tli.. 
 external nares of Corytftosuuru.s and Chintosnurus point to the presence 
 of a nasal ciiamber in these genera also. 
 
 It may be stated here that the determination of the na.sal b.,ne in 
 Stephaxosaurus rests not only on the evidence of the skull shown in Figure 
 .59H, hut also on that of fragmentary stephiinosaurinid crania in wi.ich 
 the sutural surtaces for the nasals are preserved in complete frontals 
 
 In the bram-case of the skull of Slephanosaurus (Figure 39H' .h« 
 sutures can be readily traced between the presphenoid and orbitosph ^ *. , 
 and between the orbitosphenoid and alisphenoid. Also the suture b *'""'' 
 
 etween 
 
the aiis))ht'noid und tlu? ba»<isplu-noi<i u* prom>rv(^, proving by its position 
 «hat tlif" large tlanKe, (lirected outward from iiIk»vc and soincwhat Ix-hind 
 tb*' l)aHiHph('noi(i procfss, iK'loniis to and is p«rt of tlic basisplieiioid. 
 It may l»f of interest also to note tliat in this skuU the ophtluiimiu branch 
 of the trixeniinal nerve (V; is eneli>sp<l in bone in its forward cours*' and 
 do*>»< not oecupy an ojjen cliannel a« it appears to do in Kdmontustiurus. 
 Further, iiKii<-atinK an unusually perfeet preservation of strurtural detail, 
 the wparatioii of ti«e fene«tra rotim<la from the fenestra ovalis by a hori- 
 zontuJ bar of Imne is excelletitly shown. 
 
 Tit the prejMiration of this skull l>y ('. M. SternlierR. its discoverer in 
 the fieid. are du*- many details" of stru<-tur(! that less skilful and jiainstaking 
 work wnnulil not have revealed. 
 
 Wiifb a Ijelter underitanfling «)f the stephanosHUr«ni<l skull rvrtaiii 
 errors in rhe description of t!ie skull of Chiiieosauruii i Figure SDJ; as it 
 appearefl m the l>tH^s of the Ottawa Naturalist in IVtlT, can now b<' rectitied. 
 What was B»'Karded as prefrontal i.s certainly the exjwn<le<i prolongation 
 backward of the 1ow»»t external part of the premaxilbi. and the supposed 
 sutural line ^wininf( i«!>rward from the lower >-nd ot the lachrymal (see 
 original figure is evi<W-ntly a fracture in the t)one. The convex, upper 
 surface of the diomc is nasal met in front by the upper part i^r the pre- 
 maxillary roofing the nasal passage. The bone above the orbit called 
 8upraort>Jtal in th* first instance is the pref^■^nta]. and the frontal is similar 
 to the froBftal in l>oth Stephanosnitriis and ( \'rfMhomurus in being small 
 and excluded from the orbital rim by the interv^ention of the preitrontal 
 and postfroBtal. 
 
 The powtmor hei(?ht of the skull sinwirs a marked difference in five 
 genera of crestles.s or flat-headed hadrosaurs (HadroaaiiritKBi from the 
 Cretaceous of the west of this continent, viz., in Kriiosaurus (horizon 
 uncertain = '.'Kdmonton formation), in hdmontosaurtis (EdBionton forma- 
 tion), in Grypttsaurus (Belly River formation), and in "Claosauru.i" 
 (annecUns) and IHclonius both from the Lance formation. In 
 Kritosaurun Hrown, from the Ojo Alamo K'ds of New Mexico, 
 the ([uadrate is of remarkable lengtJi, in Didomua Cope, from 
 Dakota, it is singularly short, the two repres<'Mang the extremes of skull 
 elevation and depression in the Hadmaauriim Trachodontina of Brown). 
 In these five genera, in all of which, with the exception of Kritosaurwt, 
 the skull i.- fully known from excellent material, the proportionate lengths 
 of the quadrate and skull may be expressetl in numbers as follows: Krito- 
 sa-urus 1 — over 2; (hyposanrus 1 — 2J; Ednitmtosaums 1 — over 21; "Clao- 
 munis" 1 — nearly .'5; and Didoniits 1 — nearly 4. From this comparison 
 it is seen that in Krilosaurus the posterior height of the skull (length of 
 quadrate) relative to the horiioutal length of the same is the greatest, 
 that Krilosaurus, Gryposaurua, I'Jdmontosaurus, and "Claosaurus" form a 
 series, in the order named, in which the quadrate is successively reduced 
 in length in about the same ratio, and that the greatest dififereuce in the 
 height of the skull is found between "Claosmirus" and Didonius. It 
 would appear, therefore, that as time progressed the skull in the Hadro- 
 aaurino!, as a general rule, became lower, culminating in the greattly 
 depressed and very long skull of Didonius in the closing days of the Creta- 
 ceous. The posterior height of the skull in Edmontosnurus is gri*ater than 
 the average among the genera of fiat-headed hadrosaurs in which the head 
 is known. 
 
1. 1ST OK I'HINCIPAJ, WORKS < ITKD 
 
 """^'I'u V '^■"',, -'^,''''' "" " ''"■«*' '•'^^P^i''"'' -tull from Hr.M.k.'. Isle 
 <»t WiKlit, prolml.ly .linosaurian. and MV-rahlc t,. fh.- genus Icuaiiodon 
 tiuurt. Jour. ('.col. Soc. London, vol. \.\VI1, i,„ |«t<».2(Mi nl W 
 hRs. 1-,"). • ' ■ •"• 
 
 ♦'ope K. I). Kss:i. o„ ,|„. el.ameters of the skull in the Hadrosauri.he 
 I ro( . .Vead. Nat. S.-. I'lidadel., vol. \\XV, pp. 97-107. pis. IV-VIl. 
 
 Andrews, (ha.. W. 1)S!.7. Not.- on ••. .as, of the l.rain-eavitv of Iguan- 
 .Hh.n Ann and A a^- Nat. Hist., vol. XIX. si.xth series, pp. .^S.V.'iit | , 
 ti-xt hii and pi. \\ I. h|{s. !-;{. 
 
 flay. O.I'. |..(|.... (.„ .1,,. ,kull and tlu- l.rain of Tri,eralo,>, with nof^ 
 
 on the hram-cases of Inuanodon and Me>{alosauru< I'ror I' S Nat 
 .Mus.. vol. X.X.W 1, pp. «i.-,-l08, pis. ]-;i. ■ ' 
 
 •iilinor.', (■harl..s VV. 19(1!.. Osteology of th.- .lurass,,' reptii,. ( anitrto- 
 saiirus. with :, revisi.m of the speeies of the K.nus. and .leseriptioiis 
 ot two new speeies. I'roe. I.S. Nat. Mus. v(.l. XXX \ 1 p., lUT-Mi' 
 toxt hKs. I-IM, pl.s. ti-2(i. ' ' ■ 
 
 " )sl.orn. Henry I'airfield. I-.»1L'. ( rania of Tyrannosaurus and .\llosaurus 
 Aleni AnL .Mus. Nat. Hi.<t.. new seri.-s. vol. 1. pt. I. ,,,,. |.:io. ,,i.s. 
 I-I > . text hfjs. l-2(. 
 
 Brown. M. \u\\. .\n,hi(eratop>, a new ^cnus of Horne.l -linosaurs from 
 the hdniunton ( V.'ta.'eous of .\ll.erta. With di.s.'ussion -.f the oriKin 
 ol tlie ( .Tatopsian crest an.l th.- I.rain-.'asts of .\n,-hic..ratops and 
 Iraeh.Mlon. Mull. Am. .Mus. Nat. Hist., vol. XXXIll oi. r,li<)--yis 
 fxt fiK. I, and pis. XXIX-XXXVll. 
 
 I.arnl.e. L.awr.'nee .M, |..I17. .\ new genus an.l speeies ot .■.r.-stl,.ss ha.lro- 
 saur from the K.lmonton fornmtion of All.erta. Ottawa Naturalist 
 vol. XXXI. pp. (i.-,-7;{, pis. II an.l 111. 
 
 I and,e. I.awTeiiee M. lOjS. On the genus Traeho.lon of l.,.i.lv. Ottawa 
 Naturalist, vol. XXXI. pp. I.T)-13'.». 
 
7« 
 
 INDEX. 
 
 I'* 
 
 All-plirlicml ti. '.t, 1 I. l.'i. IN. 
 
 .VtiguLir 1*1. 
 
 .Vrticubir... ti. t.'I, 
 
 liii.sl-<M'('ipitHl 't. 10. II. 
 
 Biu'isphcnoul •). II. i:{. II. :::<, 
 
 Hi'Uy Hiver fiirinatioii I. tiT. t>x. tilt. 71. 
 
 Bowcn, ('. y 
 
 Hruiii uiid bruiii-cuxi' Is 
 
 Urowii, Bnrnuiii Ii7. 71, 
 
 CtriitoiKsicla' 
 
 ( 'iTcbtlluiii "ij . 
 
 ( 'crcliruui. "i-. 
 
 CiTvical vtTlthi.i ■>7. 
 
 i'hitiioxdtiru.-^ Ii7. tis. 
 
 Ctftosfnini.'i ti7. tis. 
 
 Co]).. K. D.. 1. 
 
 t'lirythnsfiurui' li-S, 7^1. 
 
 < 'niiiiuni s, 
 
 CotyluB. !i. 
 
 Dcndv, .\ 
 
 Doiitiiiy L'. ti. .!!». II). 
 
 Dirloiiiiiii (Jo\)i liti. t>7. lis. 70. 
 
 IJii'Uttiiu!i nnrtiinlt.< 
 
 Hollo. M. \. 
 
 IX)rs:il vcrti'I)rM "is 
 
 Kotopltrygoid '_'7. :iti. 
 
 Kdmonton foriiKilioii I. 'J. '■'>, t <'7. 
 
 Ednionlosdurvs rlgati^ 
 
 The Ri'nus, 
 K.xoci-ii)itiil. 
 hViiiur. . 
 h'oni'.-it r:i . 
 
 I'oraniiiiJi II. 14. 
 
 Fore litiil) 
 
 KoMSiE. II. U. :is 
 
 rrontal li. '.t, II. Is. -Ji 
 
 < liliiiurr, C W 
 
 <rrypnsiiiiiun. Jl. It, Ii7 
 
 Uiidrosaundii I. s. Ii.s 
 
 llndromiuhrice Ii7. lis. 
 
 ILitchor, J. B 
 
 Hay, O. P 
 
 tliiiiieruN . J. ti:!. 
 
 llyjMicroiimirus ti7. 
 
 h/uanodou. 
 
 .Iiidith Hiver formation 
 
 .lugal ti. !t, n. -'tt 
 
 Kiiowlion, K. II 
 
 Krilosnurus ii7. tVs. 
 
 Lachrymal. ti. '.I. Is, JL', S.i. M. 
 
 I>an(<' formation titi. 
 
 l-oidy, Jo3«nh 
 
 Little Sandhill cirtk 
 
 liohert . .jj 
 
 Maiidihl*- 
 
 r.ii. 
 
 ■I. 10, II II. 
 
 Hi. 17. 
 
 1). Jl. J 
 
 ■Ji. 
 
 .'iS 
 
 7)» 
 70 
 10 
 7*1 
 
 !t 
 
 ;is 
 .■.I 
 
 .Vi 
 
 71 
 to 
 t7 
 til 
 :{7 
 lis 
 
 titi 
 
 li7 
 is 
 1)11 
 !» 
 IS 
 
 t>:! 
 
 IS 
 
 is 
 17 
 70 
 
 7r. 
 
 till 
 
 lit) 
 17 
 til 
 lis 
 It) 
 liti 
 :ii 
 li'.t 
 
 70 
 27 
 
 tiX 
 
 titi 
 
 71 
 
 :!s 
 
 ■•. II. II. 
 
 MaxlllaiA ii. '>. 2tV 
 
 Mt^lulla" 
 
 Milfx, A 
 
 Morrin, Albrrla 
 
 Nasal li. '.t. Is. JJ. .':t. 
 
 N'crvi'-. br.'iin cavin 
 
 cranial 
 New Mexico 
 Oeeipital condyle 
 Ojo .\l.imo bed" 
 Opi.^^tliolic li. i). 
 
 I )rbilo>plieiioiit 
 ().<b<irii, 11. I" 
 Osteology 
 I'alatine 
 Farafphenoid 
 I'arietal. ti. 
 I'ostfrontal 
 I'redeniary 
 Trefrontal. 
 I'reniaxill.irx 
 I'rc.splu'iioiii 
 I'rixitie 
 
 I'teryuoid li. !t. II. J 
 
 tjiiadrate 
 
 (iuadrato-jiiKul 
 
 KadiiiM 
 
 Ked Deer river 
 
 Hibs 
 
 Siniroliifthimr. 
 Saiirolophus 
 
 Skulls 
 
 Sfthftititlort imnrUifiis . 
 Spleuial. 
 
 Squamotial li. !t. II. 
 
 Stant<rn, T. \V. 
 Slffihfinnsa uriim 
 StiphniiDHniirux 
 SternberK, <'. M 
 Sternberg, (I. 1' 
 Sternbern, L 
 Supra-oecipital 
 SuranKiilar. 
 Teeth . . 
 'Ihorncic ribs 
 Three Hills creek 
 
 TrarbixUiu 
 
 Triiclmloii nuriibHix 
 
 Trachodoniida . 
 
 TrnchodonliiKr. 
 
 Trtreralops. 
 
 Tuatara 
 
 Itaa . 
 
 Vertebra- 
 
 Vomer 
 
 
 ti. 
 
 14. 
 
 4s 
 
 
 UN, 
 
 110 
 
 
 li.S, 
 
 nil 
 
 II. It. 
 
 IS, 
 
 4s 
 
 li. 11. 
 
 It). 
 
 4s 
 
 24 
 
 
 .*» 
 
 fit! 
 
 li. 
 
 -7, 
 
 ;i."i 
 
 !». 
 
 It. 
 
 !.-> 
 
 Iv, 10, 
 
 ■-'1. 
 
 IS 
 
 11. u. 
 
 IS. 
 li. 
 
 4S 
 41 
 
 |v. .'J. 
 
 -':i, 
 '.», 
 
 24 
 2!t 
 
 M, II, 
 
 111. 
 
 4S 
 
 '1. 17, 
 
 IS, 
 
 4K 
 
 :i7. t>7, 
 
 71, 
 
 74 
 
 J7. :iO. 
 
 ;«. 
 
 :h 
 
 . !l HO 
 
 :ti 
 
 :{.! 
 
 
 :«), 
 
 :ii 
 
 
 •> 
 
 tJ5 
 
 . -'. :i. 
 
 -'\'. 
 
 74 
 
 •J 
 
 til 
 
 !>:{ 
 
 
 11". 
 
 72 
 
 
 117. 
 
 72 
 
 ■J .'it; 
 
 70 
 
 76 
 51 
 
 li 
 
 . Hi 
 
 45 
 
 1 Is. 1! 
 
 . 20 
 
 4s 
 
 m 
 
 lis 
 
 , 7;i 
 
 ~ t ;» 
 
 ii7. lis. 
 
 74. 
 
 "."> 
 
 ■» 
 
 71. 
 
 •1 
 
 
 li. 0. 
 
 r.'. 
 
 is 
 
 i; ti 
 
 , 42 
 
 -4.{ 
 
 
 :)4 
 
 -5t> 
 
 
 fi2. 
 
 t>:{ 
 
 It). 
 
 17, 
 
 32 
 •Mi 
 
 1 
 67 
 
 
 Itl, 
 
 17 
 51 
 
 
 •> 
 
 65 
 
 
 57 
 
 11. 
 
 -61 
 37