M. Lund on Fossil Mammifera discovered in Brazil. 423 



moreover very similar to those of the Armadillos, but especially to 

 those of the Cachicames, but the bones composing the feet are short- 

 ened to such a degree, and present so considerable a flattening of the 

 articular surfaces, that nothing similar is found to occur in any animal 

 skeleton ; and it is difficult to conceive how such feet could serve to 

 burrow in the earth : moreover the form of the teeth indicates that 

 these curious animals fed solely on vegetable substances, and we 

 must suppose that they grazed in the same manner as the large 

 Pachydermata. Be this as it may, the Hoplophorus, two species of 

 which are distinguished, offer this peculiarity, that their zygomatic 

 arch is furnished with a descending branch — a character hitherto re- 

 garded as belonging exclusively to the Bradypoda. Both species 

 were of the size of an ox. Fragments of these skeletons have already 

 been described by Prof. Weiss of Berlin*. M. Lund has also disco- 

 vered some fragments. belonging to a genus allied to the preceding 

 one, and to which he assigns the name Pachytherium. Its propor- 

 tions are still heavier and its size larger. He calls this species Pachy- 

 therium magnum. 



Bradypoda. 



M. Lund thus comes to the family of the Bradypoda, which in 

 these countries performed a very important part during the antedi- 

 luvian epoch from the number and variety of its forms and the large 

 size attained by the species. 



The first genus examined is the Megalonyx, which is related to the 

 Armadillos by the osseous plates which covered a portion of the 

 body ; but these plates, besides being of an immense size, and far from 

 forming a continuous shield as in them, are separated by great in- 

 tervals from each other. 



The Megalonyx offers the greatest relations to the Megatherium 

 principally in the structure and composition of the feet ; but the 

 hinder ones present the same torsion as the feet of Bradypus tridac- 

 tylus, although arising from a different cause. In the A'i this torsion 

 is produced by the peculiar mode of articulation of the leg with the 

 astragalus ; in Megalonyx, according to M. Lund, this articulation is 

 formed in the usual way, and it is the carpian [tarsal] surface f of the 



* Mr. Owen has described in detail the structure of the dental organs and 

 the bones of the extremities of a species of this genus, to which he assigned 

 the name of Glyptodon, in reference to the sculptured form of the teeth. As 

 this description was read before the Geological Society in March, 1839 (see 

 ' Proceedings of the Geological Society', No. 62.), the name of Glyptodon must 

 take precedence of that proposed by Dr. Lund for the same extinct genus in 

 his memoir, of which the present extract was not published until the follow- 

 ing month. — Ed. 



f We presume that the term " la face carpienne" is an oversight in the 

 original Memoir. — Ed. 



