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PROCEEDINGS OF THE NATIONAL MUSEUM 



VOL. 84 



one and one-half times the length of the dorsal surfaces of the frontals. 

 It serves as a strong anchorage for the crest, which is missing in this 

 specimen. 



On the posterior border at the center the nasals are notched for a 



median forward projec- 

 tion of the parietal, but 

 .-•• '^^■■■"'[Ij^-., less deeply than in Lam- 



-'''' fh ^^^^^fK\ beosaurus.'^ The ventral 



i^^^^'^M\lf(r7 view (fig. 32, B) shows 



t^' i/ / ii ^^^A^f ^n '''Prf ^^^ T^ .^^«^* but wide 



^SX^ ,T i ^^ tMC^ ?l5_y V' contribution to the bram 



'' ''V'^\''^i/^^^ -^ •.. case in which the cerebral 



^T~ri^ i^ "^ y^ Pq portion of the brain was 



f^ I ^^ / lodged. This feature is 



\- ^^ ■^■' peculiar to the crested 



^', '^^^^0-'' hadrosaurs and much un- 



J; '^^^i^^jy'^^:^^ like the elongate com- 



"^"^"''^ pressed cerebrum of TAes- 



pesius, Edmontosaurus, 



r~^ (m^ f<~v ^^^ presumably all non- 



A fw^g' ^'''^^^\ crested forms of the 



fc^ Imi^^ ^ iiii^ Hadrosauridae. 



Alk im-^ W %. ^^'^ ^^^^^^^ borders are 



Jfl' \t<" '^ ^f^^M ^" ''''''^^'^ throughout 



f «jS%~&:^^.^^^J ^ W ^^^^^ ^'^^^^^ length with 



V ^^'^^W'm^^^^M^'^~~^ ^^^^ prefrontal and post- 



^^^^sv»\\n ,- C/ t:^"^/ 32, and thus do not con- 



^^^^^.^^^^ ^k*?"^ -^l)^^ tribute to the formation 



.pa^^^^^"^^^ of the orbital rim, as 



FiGUEE 32.-Articulated frontal bones (U.S.N.M. no. 11893): ^^^^ ^^ ^^ t-llC CrCStlCSS 



A, Superior view; B, ventral view. Fr, frontal; Na, sutural hadrOSaurS. 



surface for articulation of nasals; 0«p+c;A, sutural border for 'T"lia illiictrofinn clinwa 



orbitosphenoid and ethmoid; Pa, sutural border for parietal; ^ ^^^ lllUSirailOn S110\V S 



Po, sutural border for postorbital; Prj, sutural border for the boUC aS it is pre- 



prefrontal. One-half natural size. ^^TX^^^ with a large for- 



amen at the middle of the sutural slope. I am of the opinion that the 

 left frontal has been crushed inward against the right element and 

 that in the normal state there would be a deep gap between these two 

 elements at this point. In Lamheosaurus there is a wide open notch. 



MEASUREMENTS OF FRONTALS 



Greatest length dorsal surfaco on median line. 39 mm 



Greatest width 107 mm 



Depth of nasal suture 48 mm 



Length of brain case 30 mm 



Width of brain case 55 mm 



» Oilmore, Charles W., Geol. Surv. Canada Bull. 38, p. 37, fig. 8, 1924. 



