100 



TEETIAET VEETEBEATA OF THE FATtTM. 



prominent zygomatic arches. The cranial region is nearly twice as long as the facial 

 region. The dorsal surface is straight or very slightly concave from before backwards, 

 the highest portions of the skull-roof being the point of junction of the lambdoidal 

 and sagittal ridges posteriorly and the nasals anteriorly. The anterior prominence is 

 probably due to the deepening of the premaxillse and maxillse, resulting from the great 

 enlargement of the second pair of incisors. The orbit is very small and is open 



Eestored skull and mandible of Mceriiherium lyonsi : A, from above ; B, from left side. 

 ant.orh., antorbital foramen ; ex.oc, exoccipital ; fr., frontal ; ju., jugal ; mx., maxilla ; n., nasal ; 

 pa., parietal ; p.mx., premaxilla ; pt., post-tympanic process of squamosal ; s.oc, supraoccipital ; 

 sq., squamosal, i. 1, i. 2, i. 3, incisors ; c, canine ; pm. 2, pm. 3, pm. 4, premolars ; m. 1, m. 2, m. 3, 



molars. 



About ^ nat. size. 



posteriorly; the postorbital process of the jugal is fairly well marked, but that, of the 

 frontal is practically obsolete. The large anterior nasal opening is situated near the 

 end of the snout, but is widely separated from the alveolar border, the premaxillae 

 being greatly deepened to carry the large incisors (PI. IX. fig. 1 and PI. X. fig. 3). 

 The internal narial opening in this specimen is opposite the front of the still uncut 



