THE STRUCTURE AND RELATIONSHIPS OF ANCODUS. 487 
dorsal side the articulation is of the usual type, but the long and massive plantar pro- 
jection is firmly wedged in between the corresponding projection of mt. Ill, and the 
cuboid both proximally and externally, making a joint of great strength. Some- 
thing of the same kind may he observed in Oreodon, though much less completely 
elaborated, while the European species of Ancodus appear to be intermediate 
in this respect between Oreodon and A. brackyrhynchus, the internal projection 
from the plantar half of the cuboid being much stronger in them than in Oreodon. 
The fifth metatarsal is somewhat longer than the second and of quite a different 
shape. The shaft is more compressed and less trihedral in section, and though very 
narrow, has considerable dorso-plantar diameter. The head has a long projection 
from the posterior side, which extends beneath and appears to articulate with the 
plantar hook of the cuboid. In Oreodon this projection is rudimentary and does 
not touch the cuboid. The shaft is more compressed and less rounded than in the 
last-named genus, and less expanded distally ; the trochlea is very similar in both 
genera. 
The phalanges of the pes are very different from those figured by Kowalevsky 
xind Filhol, and, so far as the median digits are concerned, are much more like those 
attributed to Diplopus. It is, however, uncertain whether the material accessible 
to those writers enabled them to discriminate between the phalanges of the manus 
and those of the pes. In the specimen here described there is fortunately no room 
for doubt on this subject, all the bones of the hind-foot being preserved in their 
natural position and connections by the matrix. 
The first phalanx of the second digit is very much longer, more slender and 
compressed than that figured by Kowalevsky and Filhol, and has considerable re- 
semblance to the proximal phalanx of one of the median digits in the deer or ante- 
lope. The proximal end is compressed, but thick (antero-posteriorly) with a shallow, 
■concave facet for the metatarsal, which is grooved only on the plantar margin. 
The shaft is much contracted in both directions, and the distal expansion is but 
moderate. The distal trochlea is deeper than wide, is somewhat notched in the 
median line, but not at all reflected over upon the dorsal side of the bone. 
The second phalanx is hardly more than half the length of the first, but is 
relatively much stouter. The proximal trochlea is divided by a low median ridge 
into two shallow concavities, which are wider than the corresponding surfaces on 
the distal end of the first phalanx. The shaft is short and stout and somewhat 
unsymmetrical, being depressed and hollowed on the fibular side. The distal trochlea 
has a relatively larger dorso-plantar diameter than that of the first phalanx, and 
reflected more upon the dorsal side; it also is slightly asymmetrical. 
The ungual phalanx is very like a median ungual of OreodonMi\i m size and 
shape, but is more depressed, with a more regularly arched dorsal surface and blunter 
distal end. The proximal articular surface is obscurely divided into two acets of 
which that on the fibular side is smaller and more oblique in position with refer- 
ence to the long axis of the bone. Hie 
The phalanges of the fifth digit are essentially like those of the second, the 
