AMPHITHERIUM. 45 
in the matrix, the left half or ramus of the lower jaw, 
wanting the anterior or symphysial extremity, which is 
oe 
broken off. A thin layer of the original bone adheres to 
that part of the impression which indicates the articular 
condyle of the jaw @; the impression alone, which is well 
defined, gives the size and shape of the broad elevated and 
slightly recurved coronoid process (4), the base of which 
extends from the condyle to near the posterior commence- 
ment of the molar series of teeth. There is a slight rem- 
nant of the original angle of the jaw at c, which is con- 
tinued backwards, in the form of a process, to nearly the 
vertical parallel of the condyle. The part of the jaw con- 
taining the three hindmost grinders is nearly entire, only 
the outer wall of the rest of the ramus is left imbedded in 
the Oolite, and fortunately retains seven of the molars, 
with their roots entire, and undisturbed in their sockets. 
The undulations of the impression of the coronoid pro- 
cess shew that its anterior margin projected externally as a 
smooth convex ridge, and that between this ridge and the 
condyle the outer surface was slightly concave. That part 
of the angular process, which was naturally extended in- 
wards, or towards the observer, is broken away, so that 
the degree of the inward inflection is left undetermined. 
The canal for the dental artery and nerve is exposed at the 
posterior fractured margin of the jaw, filled with the whitish 
Oolitic matrix. Below this aperture begins a smooth 
moderately wide and deep groove, which is continued for- 
wards, gradually contracting to a poimt, at the lower 
margin of the jaw opposite the interspace between the true 
and false molar teeth. This groove has been described 
as a suture, or line of union, between two separate parts 
or elements of a composite Jaw : such sutures, or harmonize, 
in the composite jaws of reptiles and fishes, are simple 
