100 University of California Publications in Geology [Vol. 10 



arctos, although not found with other material representing that 

 genus. It shows a somewhat longer olecranon, and a much more 

 prominent anterior tuberosity than appears in the Oregon specimen. 

 The anterior tuberosity is also nearer the proximal border of the 

 greater sigmoid cavity in the Indian form. Lydekker called attention 

 to the similarity of the Indian specimen to the ulna of Amphicyon. 



Metacarpal 5 (figs. 17a to 17 d) resembles in general the form of 

 this element in the bears, especially that in Arctotherium. The Oregon 

 specimen differs greatly in proportions from A. simum and A. cali- 

 f ornicum of the California Pleistocene. In no. 22362 this element has 

 almost exactly the same length as specimen 30-10 representing A. simum 

 from Potter Creek Cave, but is very much thicker and heavier than 

 the Potter Creek Cave specimen. The thickness of no. 22362 approxi- 

 mates that in the type of A. calif ornicum, from the Pleistocene of 

 Rancho La Brea, but the shaft in the Rancho La Brea specimen is 

 much longer and more slender. The Oregon specimen differs from 

 the known California arctotheres in details of structure of metacarpal 

 5 as well as in proportions. In no. 22362 the distal articulation is 

 more strongly bulbous on the superior side, and the median inferior 

 keel is thicker and decidedly more prominent at the posterior end. 

 At the distal end of the superior surface of the shaft there is a marked 

 depression immediately posterior to the bulbous distal articulation, 

 whereas in the California arctotheres this area may be flat rather than 

 concave as in no. 22362. Also at the distal end of the inferior surface 

 of the shaft there is a distinct concavity in the Oregon specimen, 

 while in A. simum and A. calif ornicum this region tends to be convex. 

 In the middle of the superior surface of the shaft no. 22362 is strongly 

 convex along the anteroposterior contour, while in the California 

 Arctotherium specimens this outline is nearly straight. The proximal 

 articular face of no. 22362 is narrower transversely than in either 

 A. simum or A. calif ornicum. 



The specimen representing metatarsal 2 (figs. 18a and 18&) is not 

 as well preserved as the fifth metacarpal, and less satisfactory material 

 of Arctotherium is available for comparison. In this metapodial, as 

 in metacarpal 5, the tendency is toward somewhat greater thickness 

 than in Arctotherium, but the element does not appear relatively as 

 short compared with the corresponding element of Arctotherium as is 

 the case in metacarpal 5. At the distal end the keel is^somewhat more 

 prominent than that in a specimen of A. simum from Potter Creek 

 Cave. 



