59 



merary cervicals, it would differ from its gigantic extinct congener, and approxi- 

 mate to the Unau, in possessing eighteen dorsal vertebree ; and under any inter- 

 pretation of its vertebral peculiarities, it has two more true vertebrae than the 

 Mylodon and Megatherium. 



The spinous processes of the dorsal vertebrae are relatively shorter in the 

 existing Sloths. A few of the anterior dorsal spines in the Unau are more deve- 

 loped, but those of the posterior dorsal vertebrae are almost obsolete in both 

 species. The spinal caual is relatively smaller, but the neural arches are broad 

 and flattened, and overlap each other, though not so completely nor so exten- 

 sively as in the Megatherioids. 



The number of the dorsal vertebrae in the Ant-eaters, viz. sixteen in the 

 Myrmecophaga jubata and short-tailed Manis, seventeen in the Tamandua and 

 long-tailed Manis *, fifteen in the little Ant-eater — very closely corresponds with 

 that in the Mylodon and Megatherium. Their spinous processes, though shorter 

 in proportion to their antero-posterior breadth, present the same uniform back- 

 ward inclination. The Orycterope, which has only thirteen dorsal vertebrae, 

 has the last spine vertical, indicating a centre of motion in the trunk ; and both 

 those behind and those before have a converging inclination towards this centre. 

 The Armadillos present an uniform backward inclination, and a nearly equal 

 development of their dorsal and lumbar spines ; but they deviate more than 

 the Orycterope from the Megatherioids in the smaller number of their dorsal 

 vertebrae, which does not exceed eleven in some species, nor twelve in any. 

 The posterior dorsal vertebrae of the mailed Edentates likewise differ in a 

 much more important character, which immediately relates to the support of 

 their peculiar osseous covering, and is so conspicuous and obvious in its rela- 

 tions, as to have merited, though it has not hitherto received, the attention of 

 those anatomists who have confidently attributed a similar bony covering to the 

 Megatherium. 



The anterior oblique processes begin, at the middle of the dorsal region, in the 

 Armadillos, to send a process upwards, outwards and forwards, which, progress- 

 ively increasing in the posterior vertebrae, attains in the lumbar region a length 



* Cuvier ascribes only thirteen dorsal vertebrae to the Phatagin (^Ufanis longkmdata) , but the skele- 

 ton of this species in the Hunterian Museum shows seventeen. 



H 2 



