1916] Merriam— Stock-Moody : An American Pliocene Bear 109 



shows a M5 not differing materially from that of Arctotherium. M 5 is 

 large and elongate, approximating the form seen in typical Pleistocene 

 Arctotherium, as in A. simum. 



The type specimen of Proarctotherium evidently represents a 

 typical member of the Arctotherium group. As the occurrence of 

 a representative of the Hyaenarctos type seems now fairly established 

 for the late Tertiary of Mexico, it is of course possible that a member 

 of the group reached South America with the earliest of the Pliocene- 

 Pleistocene emigrants from North America. While the characters of 

 I? in the Parana form do not differ greatly from those of Hyaenarctos, 

 is of a distinctly more advanced type. The nature of the 

 specialization of M s is such as we commonly find associated with an 

 anteroposterior^ elongated heel of the last upper molar, and is not 

 to be expected in a Pliocene bear. Apparently the geologic occurrence 

 of the Parana specimen must remain in doubt until other material of 

 this nature appears in the Parana. 



Transmitted October 25, 1916. 



