SKELETON OF BRUTA. 407 



mandible is deepened for the long roots and matrices of the ever- 

 growing molars. The extension of the air-sinuses, great in the 

 climbing Sloths, was still more so in the colossal species, whose 

 strength enabled them to uproot and prostrate the trees they 

 browsed on. The skull of the Mylodon robustus in the Hun- 

 terian Museum shows two extensive fractures of the outer table, 

 one wholly, the other partially, healed : the latter extending to 

 near the occiput, but having broken only into the air-chamber, 

 not into the cranial cavity, the inner, proper or ' vitreous ' table of 

 which is everywhere divided by sinuses and sinuous bony plates 

 from the outer table. 



Notwithstanding the extreme diversity — singular contrast in- 

 deed in several particulars — which the skull presents in the order 

 Bruta, the marks of inferiority of position in the Mammalian 

 series, according to the cerebral character, are constant through- 

 out. The terminal position of the occipital condyles and the 

 aspect of the occipital surface, the degree in which the parts of 

 the complex ' temporal bone ' of higher Mammals retain their 

 primitive separation, the position of veins conducting from the 

 cerebral sinuses, the low facial angle and small proportional size 

 of the cranial cavity, the small share in which the squamosal 

 contributes to its walls — all exemplify the inferiority of the 

 present unguiculate group of animals to the Gyrencephalous 

 Ungulates. 



C. Bones of the Limbs. — In all Armadillos the clavicles, fig. 

 275, 52', are complete. The scapula, 

 51, is broad, convex externally, and 

 presents two spines, the normal one of 

 which is produced into an acromion, 

 long in all the species and unusually 

 so in the Chlamyphore, ib. n ; in most 

 it sends down a process from its base. 

 The coracoid curves downward: there 

 is a well-marked tubercle behind the 

 neck of the scapula. The suprasca- 

 pular element is represented by a Bones of foreiimb, chiamyphore, 

 coarsely ossified cartilage attached to 



the base of the scapula, fig. 260, 51. The humerus is remark- 

 able for its strength and for the great developement of the deltoid 

 ridges. It is perforated above the inner condyle, but not be- 

 tween the condyles. The ulna, fig. 276, 55, is considerably 

 longer and stronger than the radius : the olecranon, fig. 275, 

 54, is remarkably developed. In Dasfjpus the radius, fig. 276, 



