108 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxxvi. 



of air sinus; soc, supraoccipital ; r, opeuiug for supijosed veiu ; a; cavity in 

 basioccipital; /, 2, 3, Jf. 5. 6, 7, 8, !>. 10. 12. exits for nerves of correspondiii.i? 

 numbers. 



Plate 3. 



Brain-casts of two species of Triceratops. 



Fig. 1. Triceratops scrratus. Upper surface. X §. 



2. Trk-vratops scrratus. Low-er surface. X §. 



3. Triceratops serratus. Right side. X §. 



4. Triceratops sulcatum. Right side. X i. 



car, entrance of carotid artery into pituitary fossa ; ccb. p process of 

 cerebellum; cer. h, cerebral hemisphere; mcd, medulla oblongata; olf. 1, olfac- 

 tory lobe; op. a, base of supposed ophthalmic artery; op. I, optic lobes; pit. 

 pituitary body, largely restored in tig. 2; r, veins; 2, 3, J, optic, oculomotor, 

 and trochlear nerves; .7, ophthalmic branch of 5th nerve; .T ^' ^ maxillary and 

 mandibular branches of 5th nerve; 6, 7, 8, abducent, facial, and auditory nerves; 

 10, pneumogastrie nerve, with probably the glossopharyngeal and the spinal 

 accessory ; 12, hypoglossal nerve. 



