21 



the anterior margin of the maxillary; for there is as little trace of an inter- 

 maxillary suture as of the bone itself. 



Another of the pecuUar features of the side-view of the Mylodon's skull is 

 the inferior line of the bony palate, which is seen extending half an inch lower 

 than the grinding surfaces of the upper molars, in consequence of the shortness 

 of their exposed crowns, and the convexity of the palate. The anterior border 

 of the palatal process of the superior maxillary extends nearly an inch in ad- 

 vance of the external and inferior angular process of the same bone. 



In the side-view of the skull, the broad ascending ramus of the lower jaw is 

 seen applied, by the transverse condyle, to the flat glenoid articulation at the 

 base of the zygoma, sending its broad coronoid process upwards into the tem- 

 poral cavity, and its angular process backwards as far as the vertical Una dropped 

 from the posterior root of the zygoma. The ridges and depressions on the 

 angle indicate the place of insertion of those protractor fasciculi of the strong 

 masseter which took their origin from the depending plate of the malar bone. 

 The horizontal ramus gradually diminishes in depth towards the symphysis, 

 which slopes forwards from below towards the anterior margin, which is very little 

 in advance of the vertical line dropped from the extremity of the nasal bone. 



Three of the inferior teeth are visible when the mouth is closed ; the fourth 

 being concealed by the malar bone. 



Upper view*. — The upper, like the lateral surface of this singularly-shaped 

 skull, presents the form of a parallelogram, which is shghtly contracted at the 

 middle third included by the zygomatic arches, and a little expanded at the two 

 extremities ; the anterior expansion being scarcely of less breadth than the pos- 

 terior one. This is formed by the thick occipital or deltoidal ridge ; behind 

 ■which the sloping posterior region of the cranium, and the widely separated oc- 

 cipital condyles, come into view. 



The upper surface of the skull is uniformly smooth ; gently convex, both 

 transversely and longitudinally ; almost flat in the parietal region ; a little raised 

 above the orbits, and as much depressed at the root of the nose. It is bounded 

 laterally by two longitudinal ridges, slightly overhanging the sloping sides of the 

 skull, and describing three successive curves, with their concavities directed out- 



* Plate III. 



