EOTIIEKIUM yEGYPTIACUM. 
207 
forms tlie posterior border of the large anterior ])alatine foramen (a.p.f.). Behind 
this the palate is deeply concave from side to side, but on either side is raised into a 
])rominent ridge lying just within the alveolar border and extending back to the level of 
the alveolus of the tooth here regarded as 2. Behind this, the palate widens out, its 
greatest width being about opposite the front of m. 2. The transverse suture with the 
palatines is about opposite the i’ront of m. 1 ; the posterior palatine foramina are either 
very small or absent. On the outer side of the maxilla the broad zygomatic process 
rises by a very long base, and its ventral surface is very little above the alveolar border ; 
the antorbital foramen (a.o.f.) is smaller than in Eosiren. The suture between the 
jugal (ju.) and maxilla is not very distinct, at least posteriorly ; probably the relations 
of the two elements were almost as in Manatus ; at any rate, it is clear that the jugal 
made a broad squamous overlap on the upper surface of the zygomatic process of the 
maxilla, so that it forms the actual floor of the orbit. Behind this, it widens out 
suddenly, being produced downwards into a blunt point and upwards into a slight 
postorbital process. Posteriorly it becomes a mere rounded rod of bone underlying 
the zygomatic process of the squamosal. 
The palatines {pi.) form the greater part of the palate as far as the front of the 
molar series. The posterior border of the palate seems to have been a little behind 
the last molar, but in this specimen it is somewhat incomplete. The descending plates 
bounding the mesopterygoid fossa no doubt are formed by the palatines in front and 
the pterygoids behind, but tbe sutures are indistinct ; the same is the case with the 
junction of the lower part of the alisphenoid with the pterygoid. The body of the 
alisphenoid {al.) joins the parietals above, the squamosals behind, and the frontals in 
front ; its lower border forms the outer lip of a deep groove, at the bottom of which 
the optic and other foramina opened ; this groove is continued forwards to the orbit 
by the lower edge of the frontal. The orhitosphenoid is not distinct. The tympanic 
[ty.) is incomplete on both sides. 
The dentition in this specimen is of great interest. The dental formula seems to 
have been : i. 3, c. 1, y)ui. 4, m. 3, The anterior incisors are very remarkable teeth, and 
as in the later forms they are situated at the end of the snout, while they are already 
somewhat enlarged. They have very long roots, and their enamel-covered crowns are 
a little compressed from side to side ; the anterior border is rounded, the posterior 
sharp. The outer face is flat or slightly convex, while the inner is raised into vertical 
ridges, so that the worn surface of the tooth has the appearance shown in text-fig. 66, B, 
looking almost as if it were a complex tooth composed of several elements. The thick 
enamel has a peculiar appearance, owing to the development of numerous obscure 
wrinkles. Behind these teeth there is a diastema of considerable length separating 
them from the second incisors, which were large teeth situated on the edge of the 
premaxilla and not displaced outwards as in Eosiren. Immediately behind these were 
the third incisors, the posterior borders of the alveoli of which are in contact with the 
