132 FOSSIL MAMMALIA. 



regard to the system of dentition, to the form of the head, and 

 the composition of the extremities. 



As for the megalonyx, but one tooth and a few bones be- 

 longing to the limbs have as yet been collected ; but those relics 

 are sufficient to prove its approximation to the megatherium, 

 though it must be considered specifically different. 



Both were at least as large as the ox. Their limbs were 

 robust, and terminated by five thick toes, of which only some 

 were provided with an enormous claw, arched and crooked like 

 the claws of some tatous, ant-eaters, and bradypi. The mega- 

 therium, of which a clearer idea may be formed than of the 

 megalonyx, had a small head, short muzzle, terminated, per- 

 haps, by a short proboscis, the mouth furnished only with 

 molars, whose coronals were marked with transverse hillocks. 

 The neck was moderately short; the body voluminous and 

 heavy ; the limbs extremely robust, and the anterior ones pro- 

 vided with powerful clavicles. Recent observations seem to 

 prove, that if it had analogies with the bradypi, in the forms of 

 the head and dentary system, and with the ant-eaters in the 

 conformation of the extremities, it also resembles the tatous in 

 the nature of its teguments. Its skin, thick and, as it were, 

 ossified, was divided into a number of polygonous scales, ap- 

 proximating one to the other, like the pieces which enter into 

 the composition of mosaic work. 



The form of the molars, and the size of these animals, seem 

 to indicate that they fed on vegetables and roots. The confor- 

 mation of their limbs shows that their walk must have been slow 

 and equal. Their debris have been found only in America. 



The megatherium, sometimes called the animal of Para- 

 guay^ was discovered towards the end of the last century. 

 The skeleton, almost entire, was found nearly at one hundred 

 feet of depth, in excavations made in the midst of an ancient 

 alluvial stratum, on the banks of the river of Luxan, a league 

 south-east of the town of the same name, which is three leagues 

 west-south-west of Buenos Ayres. It was sent to the museum 



