PLATE 10 
Lateral surface of the left ulna and radius; about two-fifths natural size. 
Figs. 46 and 47. No. 8987, Castor subauwratus. 
Figs. 48 and 49. No. 12654, Castor subauratus. 
Figs. 50 and 51. No. 12668, Castor subauratus. 
Figs. 52 and 53. No. 16385, Castor subauratus. 
Figs. 54 and 55. No. 19229, Castor fiber. 
Figs. 56 and 57. No. 210, Castor canadensis phaeus. 
Figs. 58 and 59. No. 4347, Castor canadensis belugae. 
Figs. 60 and 61. No. 12101, Castor canadensis leucodonta. 
Note that the plane of the proximal articulating face of the radius is set at 
an angle of about 90 degrees with the shaft in fiber and canadensis, but is tilted 
in subauratus; the greatest diameter of the neck of the radius is less in cana- 
densis; the head of the radius rises more abruptly in canadensis. In swbauratus 
the fossa below the interosseous crest is shallower, at its proximal end, than in 
canadensis and fiber. 
[110] 
