PLATE I 



Cenlrosaurus apertus. Head, about one-tenth natural size. 



Ang. angular; ant. p. anterior process of frill; art. articular; 'cp. I, coronoid; cp.2, 

 coronoid process; D dentary; e.p. epoccipitals; epi. epijugal; ¥ frontal; ] jugal; 

 L lachrymal; M maxilla; N nasal; n.h.c. nasal horn core; O orbit; P parietal; 

 post p. posterior process of frill; pre.d. predentary; pre.m. premaxilla; p.f. 

 prefrontal; po.f. postfrontal; Q quadrate; q.j. quadratojugal; ros. rostral;'S.ang. 

 surangular; s.h.c. supraorbital horn core; sp. splenial; sq. squamosal. 



PLATE II 



Centrosaurus apertus. Right mandible, external view, about one-fifth natural size. 

 Lettering as in Plate I. 



PLATE III 

 Cenlrosaurus apertus. Part of left mandible, internal view, about .35 natural size. 

 Lettering as in Plate I. 



PLATE IV 

 Centrosaurus apertus. Right thyrohyal, about five-sixths natural size; left figure, 

 upper view; right figure, lower view. 



PLATE V 



Centrosaurus apertus. 



Fig. 1. Anterior cervical vertebrae. Greatly reduced. 

 Fig. 2. Left humerus, external view, about one-eighth natural size. 

 Fig. 3. Left scapula and coracoid, about one-seventeenth natural size. 

 Fig. 4. Right scapula and coracoid, about one-twelfth natural size. 

 Fig. 5. Left manus, greatly reduced. 



