132 BULLETIN 89, UNITED STATES NATIONAL MUSEUM. 



Plate 5. 



Skull of Stegosaurus stenops Marsh. Side view. Type. Cat. No. 4934, U.S.N.M. i nat. size. 

 a, anterior nares; an, angular; ar. articular; 6. orbit; c. infratemporal fossa; d, dentary; j, jugal; I, 

 lachrymal; m, maxillary; n. nasal; oc. occipital condyle; p. ar, prearticular; pd, predentary; pf, pre- 

 frontal; pm, premaxillary; p.o, postorbital; p. oc, paraoccipital process; po. so, postsupraorbital: p. so, 

 presupraorbital; q. quadrate; qj, quadratojugal; s. splenial: sa. surangular; sq, squamosal. See p. 27. 



Plate 6. 



Skull of Stegosaurus stenops Marsh. Top view. Type. Cat. No. 4934, U.S.N.M. J nat. size. 

 e, supratemporal fossa;/, frontal; I, lachrymal; m, maxillary; n, nasal; p, parietal; pf, prefrontal; 

 pm, premaxillary; po, postorbital; p. oc, paraoccipital process; po.f, postfrontal; po. so, postsupraorbital; 

 p. so, presupraorbital; q, quadrate; qj, quadratojugal; so, supraoccipital sq, squamosal. See p. 27. 



Plate 7. 



Skull of Stegosaurus stenops Marsh. Type. Cat. No. 4934, U.S.N.M. i nat. size. Inferior view. 

 an. angular; ar, articular; d, dentary; oc, occipital condyle; p. ar, prearticular; pd, predentary; pi, 

 palatine; pm, premaxillary; p. oc, paraoccipital process; pi, pterygoid; s, splenial; v. vomer. 



Drawn under the direction of Prof. O. C. Marsh, with slight modifications. See p. 27. 



Plate 8. 



Skull of Stegosaurus stenops Marsh. Longitudinal section. Type. Cat. No. 4934, U.S.N.M. 

 i nat. size, a, anterior nares; an, angular; ar, articular; d, dentary; /. frontal; f.m, foramen magnum; 

 m, maxillary; n, nasal; oc, occipital condyle; p, parietal; p. ar, prearticular; pd, predentary; pm, pre- 

 maxillary; p. oc, paraoccipital process; pt, pterygoid; q, quadrate; s, splenial. 



Drawn under the direction of Prof. O. C. Marsh, with slight modifications. See p. 27. 



Plate 9. 



Skull of Stegosaurus stenops Marsh. Cat. No. 4934, U.S.N.M. £ nat. size. Type. (1) Front view; 

 (2)backview. a, anterior nares; an, angular; ar, articular; d. dentary;/, frontal; fin, foramen magnum; 

 I. lachrymal; n, nasal; oc, occipital condyle; p, parietal; p. art, prearticular; pd, predentary; pf, pre- 

 frontal; pm, premaxillary; po, postorbital; p. oc, paraoccipital; po. f, postfrontal; po. so, postsupra- 

 orbital; p. so, presupraorbital; pt, pterygoid; q. quadrate; sa, surangular; so, supraorbital, sq. squa- 

 mosal. Both figures after Professor M?rsh. with slight modifications. See p. 27. 



Plate 10. 



Skull of Stegosaurus armatus Marsh.? Cat. No. 4936, U.S.N.M. 1. Top view; e, supratemporal 

 fossa;/, frontal;/??i, foramen magnum; ns, sutural surface for nasals; oc, occipital condyle; p. parietal; 

 po. postorbital; ps, sutural surface for prefrontal; so, supraoccipital. 2. Ventral view; al. sp, alisphe- 

 noid; b, orbit; e. supratemporal fossa; oc, occipital condyle; ol. olfactory region of the brain case; or. sp. 

 orbitosphenoid; pp, paraoccipital process. II, III, and IV exit of second, third, and fourth cranial 

 nerves. 3. Longitudinal section through brain case; / frontal; /', exit of II cranial nerve; fm, foramen 

 magnum; oc, occipital condyle; ol, exit of olfactory nerve; op, for optic lobe; p, parietal; pi, pituitary 

 fossa; ps, presphenoid; so, supraoccipital. 4. Outline of skull of Stegosaurus armatus with brain cast 

 in position; seen from above; c, cerebral hemispheres; cb, cerebellum; e, supratemporal fossa; in, 

 medulla; ol, olfactory lobes. 5. Brain cast of the same; c, cerebral hemispheres; cb, cerebellum; m, 

 medulla; ol, olfactory lobes ; on, optic nerves; op, optic lobes; pi, pituitary body. All figures are \ nat. 

 size. Drawn under the direction of Prof. O. C. Marsh with slight modifications. The species identifi- 

 cation is that of Professor Marsh. See p. 41. 



