AMPHITHEEIUM. 45 



in the matrix, the left half or ramus of the lower jaw, 

 wanting the anterior or symphysial extremity, which is 

 broken off. A thin layer of the original bone adheres to 

 that part of the impression which indicates the articular 

 condyle of the jaw a ; the impression alone, which is well 

 defined, gives the size and shape of the broad elevated and 

 slightly recurved coronoid process (5), 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 point, 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 harmonise, 

 in the composite jaws of reptiles and fishes, are simple 



