270 



from the back part of the dental orifice where it is broadest, backward, becoming nar- 

 rower as it recedes, and subsiding an inch and a half from the orifice. 



About 3 inches, following the curve, of the back part of the base of the coronoid (r,f) 

 are preserved ; its commencement from the neck of the condyle (r) is raised much above 

 the horizontal plane of the molar alveoli : the plate here is thin, but its margin is obtuse 

 or rounded ; at the hind part of the fracture (/'') it shows a thickness of 2 lines ; as it 

 advances it gains one of 3 lines; as the anterior border descends it gradually increases 

 in thickness to lines, near its obtusely rounded basal beginning. This (fig. 1, q), as 

 usual, rises, buttress-like, from the outer wall of the mandible, on the transverse parallel 

 of the middle of the last alveolus, and about an inch and a half lower than the outlet 

 of that socket. The course of the base of the coronoid upward and backward is with a 

 Blight outward concavity at its anterior half, and is then level; its extent is 4 inches 

 9 lines ; the anterior border of the process is gently convex, to the extent (4 inches) to 

 which it has been preserved. The breadth of so much of the condyle (c) as is preserved 

 is 2 inches 3 lines ; the outer portion shows a small part of the articular surface, convex 

 from before backward. 



The ectocrotaphyte depression (fig. l,f) is smooth and shallow ; it is divided from the 

 lower inflected part of the ascending ramus by a change of contour of the smooth outer 

 surface, forming a broad convexity vertically; but this becomes, as it recedes, rather 

 more prominent, thinner, and shows a roughened, as it were worm-eaten, surface (fig. 1, h), 

 and, from a slight inflection at its termination towards the back surface of the ascending 

 ramus, it there indicates the fore-and-aft extent of that part of the jaw as giving, viz. 

 from the fore part of the base of the coronoid, G inches. It is possible that a smoother 

 surface of the hind prominent outer and lower boundary of the ascending ramus may 

 have suffered some abrasion in the fossil. There is no perforation of the crotaphyte 

 depression. 



The symphysial end of the present ramus has been broken away at the fore part of 

 the second alveolus, exposing part of the anterior root of that tooth (fig. 4, d *), and a 

 small part of the bottom of the incisor's socket (/). 



The antero-posterior extent of the last three molar sockets is 4 inches 10 lines ; a thin 

 plate rises to form the outer wall of their outlets. 



The inbending of the inner surface to form the hind part of the symphysis begins at 

 the vertical parallel of the middle of the third molar (fig. 2, s, m i). The lower part 

 of the symphysis shows a pair of transversely crescentic insertional depressions, concave 

 backward (fig. 3, v, v). The depth of the ramus at the interval between the third (m i) 

 and fourth (m 2) sockets is 2 inches 8 lines : in the female (X) of Nototherium Mitchelli 

 it is 3 inches ; in the male (?) it may attain 3 inches 10 lines. 



The symphysial joint in Nototherium Victoria? has become completely obliterated in 

 the present full-grown specimen ; a dense, minutely spongy tissue is included in a thin 

 compact crust of bone. 



The inner wall of the alveolar outlets does not rise so high as the outer one ; it thins 



