NOTODIAPHORUS CRASSUS 35 
condyles there is a deep rugose pit for the plantaris muscle, 
and on the anterior side the suprapatellar fossa is well 
marked. The condyles are placed a trifle obliquely; the 
internal one being shorter and with a rounded articular 
face, the external condyle being longer, and with a flat- 
tened articular face which slopes obliquely inward. 
Of the tibia, only the distal end is preserved. This in- 
dicates a rather slender bone, with a shal- 
low, fairly wide concavity for the external 
astragular trochlea, and a narrower and 
deeper concavity for the internal astragu- 
lar trochlea. On the internal side of the 
tibia there is a rugose surface for the fibula. 
An isolated lower end of a fibula indi- 
cates a slender bone, enlarged distally 
where it comes in contact with the tibia. 
The fibula carries on its inner face a mod- 
erately large facet for the external side 
of the astragulus, and on the distal end a 
wider one for contact with the calcaneum. 
The tarsus 1s compactly built, wider 
than that of Diadiaphorus, because the 
external digits are not as much reduced. 
This especially shows in the greater de- rig. o. Distalendof left 
velopment of the cuboid and the meso- ae ea 
cuneiform, but in other features it is similar to that of its 
descendant. 
The astragulus is a very characteristic bone. The trochlea 
is asymetrical, the external condyle rising higher than the 
internal, and the median groove being wide and shallow. 
On the nearly vertical outer face of the astragulus, there 
is asemicircular band-like facet for the fibula. The trochea 
extends well around the top of the bone, allowing a wide 
movement of the foot. The neck of the astragulus is long 
and wide, carrying a broad flattened head, with its con- 
vex facet for the navicular, covering the entire end. On 
