98 



brain had been disposed in a few simple parallel longitudinal con- 

 volutions. 



The lower jaw resembles, in the general form of the posterior moiety 

 which is here preserved, that of the Sloth and Mylodon more than that 

 of any other edentate species. Its deep posterior angle is produced 

 backwards, and a broad coronoid process rises and nearly fills the 

 zygomatic space ; the condyle is flat, as the glenoid surface has already 

 indicated ; its transverse diameter is an inch and eight lines : its antero- 

 posterior diameter seven lines : it is principally extended inwards beyond 

 the vertical line of the ascending ramus. The lower contour of the jaw 

 describes an undulating line, which, commencing from the posterior 

 angle, is at first gently convex, then slightly concave, then again convex 

 below the alveoli of the teeth, where it is rounded and expanded as in 

 the Orycterope. 



The fractured condition of the right ramus of this part fortunately ex- 

 posed the roots of the four grinding teeth, which constitute the dental 

 series on each side of the lower jaw. The length of the jaw occupied by 

 these four alveoli is three inches ten lines, which exceeds a little that of 

 the opposed five grinders above ; the ramus of the jaw gradually dimi- 

 nishes in all its dimensions anterior to the molar teeth ; the dental canal 

 passes in a gentle curve below and on the inner side of the alveoli, 

 whence it gradually inclines to the outer wall of the jaw. 



The whole ascending ramus of the jaw consists of a very thin plate of 

 bone : it is slightly concave on the inner side, and the inferior margin of 

 the produced angle inclines inwards as in the Mylodon and Sloth : it is 

 impressed on the outer side with two shallow depressions, and two 

 parallel ridges, both following the gentle curvature of the part. There 

 is a foramen on the outer side of the ramus at the anterior part of the 

 base of the coronoid process corresponding with that in the lower jaw of 

 the Mylodon, but the longitudinal channel which runs along the outer 

 side of the alveolar process is wanting, and the expansion at the base of 

 those processes is more sudden and relatively greater : the general cor- 

 respondence, however, between these lower jaws is such as would lead 



