pas 
v2 
ae 
, 
A Skeleton of Great Fossil Beaver, Castoroides Ohtoensis. 167 
Its base also is twisted with the bottom inward, terminating in a 
powerful inferior tuberosity. Its shaft bends slightly outward from 
the middle toward the distal end. ‘This bending away from each 
other of Nos. III and IV, is not seen in the recent beaver foot 
used in this comparison. No. IV projected slightly the farthest 
back of any in the series, bearing a shoulder against a spur 
of No. III, and pushing its base back, occupied the full face of 
the cuboid. ‘The articular face is not so convex as in Castor. 
No. V is but a magnified view of the corresponding member of 
Castor: a broad base exteriorly, gibbous below, with a flattened 
tuberosity which slants forward along the under side of the shaft 
into a low crest, an oblique concave articular surface, which fits to 
a convex condyle near the under, outer base of No. IV, the whole 
base and nearly half of the shaft being nearly concealed under the 
larger member with which it joins, so that its proximal end does 
not touch any metatarsal. ‘he articular surface is three-fourths of 
an inch long by one-third of an inch wide. The shaft bends 
gently outward, through nearly half its length toward the distal 
end, and a very little downward. 
The first phalanx of No. III was found, and also the first and 
second phalanges of No. IV, which is the longest and most pow- 
erful of the metatarsals. 
Nos. J and V look as though they might have been nipped off 
and healed while the subject was still alive, and the first phalanx 
of No. IV appears to be deformed at its base, as if it had at some 
time received an injury. Itis abnormally large, and the toe is bent 
to one side. (Was the poor fellow caught by the foot in some pre- 
historic trap? ). 
The distal ends of all the metatarsals have the articular surfaces 
very convex, vertically, the lower half of-the face, as it bends 
under and backward, being double, having a very short ridge, on 
either side of which is a groove. By this means a strong hinge 
joint is produced when the toes are flexed, and a partially ball 
and socket joint when the same members are extended. 
The proximal ends of the first series of phalanges are concave, 
with a sharply-defined notch in the lower border of the articular 
surface. These notches cover the sharp, spur-like ridges of the 
distal ends of the metatarsals, as already described. 
The sharply-defined, well-pitted and roughened scars which 
mark the attachments of the various ligaments and tendons, indi- 
cate how powerfully the parts of the feet were held together. 
