8 
TEliTIAliT VEUTEERATA OF THE FAYOM. 
situated hetweoii the ii|)])er edges of the facial processes of the premaxillae: this 
will he described Jiiore fully in the account of the latter bones. The anterior 
face of the ])renasal bar is flattened and towards its lower end deeply pitted by 
what seem to be muscle-impressions: possibly the animal possessed a pointed mobile 
upper lip, something like that of lildnoceros hicornis, and the muscles inserted in 
these impressions were concerned in its movements. The general form and relations 
of the prenasal bar are well shown in PI. I. and PI. II. fig. I a; also in text-fig. 2. 
Text-fig. 2. 
Skull of Arsinoiilierium zitteli: oblique view of anterior portion showing the relation 
of the nasal and maxilla in the narial opening. 
a. 0 . f., antorbital foramen; f. 1, f. 3, incisors ; ji’m., jugal; lachrymal; nics., prenasal bar; wies.f/., mesethmoid 
groove ; «i.r., maxilla ; na., nasals ; nar., nares ; pm. 2, pm. .3, premolars ; pmx., premaxillcC. ] nat. size. 
I'he horns themselves are borne on a common base, formed by the frontals 
posteriorly, but for the rest by the nasals alone. The mid-dorsal line of the 
basal portion is marked by a shallow groove, but in the adult the median suture 
is completely obliterated. A section of the basal region taken at right angles to 
its dorsal surface would give an arc of about three quarters of a circle, though 
somewhat inflated at the sides. From this base the paired horns arise and project 
forwards, upwards, and somewhat outwards. In adult, probably male, animals they 
