No. 398.] ANGULATION OF LIMBS. 91 
anterior and posterior intersecting edges of the proximal and 
distal articular surfaces or facets. 
Several facts are at once brought out by these sections which 
bear upon the arthrology of the Ungulate limb. 
(1) As the humerus, in the descent from the primitive bent- 
limbed types, is directly more vertically forwards, the articular 
facets are tilted from an oblique angle to more nearly a right 
angle with the shaft. 
(2) At the same time the proximal or scapular facet shifts 
forwards, while the distal or ulno-radial facet shifts backwards 
Fic. 4. — Mother elephant “ Hebe” and baby “ Americus,” showing the excessive straightening 
over extension of the fore limb, (By permission, from a copyrighted photograph by 
iber & Sons, Philadelphia.) 
upon the shaft’s axis. An extreme instance of such shifting is 
Shown in the transition from the rhinoceros (Fig. 3) to the 
elephant type (Fig. 1). 
(3) The proximal and distal articular facets shift uniformly, 
and their edges are always found to be in nearly parallel planes, 
b-b, bb. 
In the straight-limbed Proboscidia and Dinocerata, by this 
means the proximal articular facets of the humerus come to lie 
almost directly upon the top of the shaft. In the Dinocerata 
the articular facets are slightly more inclined to the axis of the 
shaft than in the Proboscidia. The difference, however, is 
