134 



TERTIAET VEETEBRATA OF THE EATtTM. 



and the exoccipital, internally by the basioccipital and basisphenoid, and anteriorly by 

 the alisphenoid, the foramen lacerum medium {f.l.m.), and perhaps the pterygoid. 

 Externally the bone seems to send a narrow wedge-shaped process between the 

 post-tympanic process and the inner end of the glenoid surface, thus helping to 



Teit-fig. 49. 



A. 



B. 



■fill. 



The base of the skull and part of the palate of : A, Pdlceomastodon ; B, Elephas. 



ol.c, alisphenoid canal ; a7«., alisphenoid ; a.o.f., antorbital foramen; 6oc., basioccipital ; 6sp., basisphenoid; 

 <;m., eustachian opening; exo., exoccipital; f.l.m., foramen lacerum medium ; /.Z.^., foramen lacerum 

 posterius ; f.o., foramen ovale ; gl., glenoid surface for mandible ; i.c.c, foramen for internal common 

 carotid ; i.n., internal nares ; ju., jugal ; m. 2, m. 3, second and third molars ; pi., palatine ; p-p-f--, 

 posterior palatine foramen ; pp., paroccipital process ; pt., pterygoid ; pty., post-tympanic process of 

 squamosal; st.mf., stylo-mastoid foramen ; <j>.A., tympano-hyal ; ty., tympanic; v., vomer. -I- nat. size. 



form the floor of the inner end of the external auditory meatus. In front of this the 

 bone is excavated by the deep fossa referred to above ; this seems to have opened i nto 



