186 



THE AMEBIC AN NATURALIST 



[Vol. XLVI1 



modern Alligator skull. After comparison with Diplocynodon, 

 Alligator and Bottosaurus, all members of the Alligatoridae, 

 Gilmore has described the new alligator as Brachychampsa 

 montana, new genus and species. He gives as the fundamental 

 generic character of the form 



In the absence of a roof-like covering formed by the premaxillaries 

 over the anterior part of the external nares. /.' r«< li iiclunn />*(( differs from 

 all known alligators, both recent and extinct. 



Some of us may be inclined to question the validity of this 

 character for a genus but further study will doubtless establish 

 the form on a safe basis. 



Dr. W. D. Matthew has reviewed briefly 2 the ideas relative to 

 the posture and habits of life of the great ground sloth, Mega- 

 therium, and its allies from the Pleistocene of North and South 

 America. Under Dr. Matthew's direction there has been pre- 

 pared a small group of four of these large brutes in the atti- 

 tudes which have been suggested as possible by the study of 

 their skeletal anatomy. Two genera are represented — Lesto- 

 don and Mylodon. The L< stodon skeleton is mounted in the 

 familiar pose of the Megatherium reared against a tree trunk 

 and one Mylodon is digging at the roots of the same tree. The 

 writer says : 



These poses illustrate the theory of the habits of the ground sloth de- 

 duced by Owen from the study of the skeleton— a model of scientific 

 reasoning whose accuracy has never been impugned. 



The same writer in a short article 3 describes a recently 

 mounted skeleton of Agriochoerus as "a tree-climbing rumi- 

 nant." The history of this genus is interesting in that 

 its various parts have been referred to no less than three mammalian 

 orders, the head to the artiodactyls, the fore foot to the creodonts and 

 the hind foot to the Ancylopoda. 

 Dr. Matthew opens his paper with the remark that 



It seems somewhat paradoxical to imagine a ruminant climbing trees. 

 He says further: 



The Agriochoerus, however, while a member of the Oreodont family, 

 and like them provided with ruminating teeth, had the limbs and feet 

 modified in such a way as to enable it to climb trees as readily as a 

 jaguar or other large cat. 



'American Museum Journal, XI, No. 4, p. 113. 



'American Museum Journal, XI, No. 5, pp. 162-163. 



