MESODONTA. 
139 
unless it be the fragment of the shaft of the femur. Yet this agrees in 
proportions with the associated pieces. The large individual is represented 
by many fragments, including portions of vertebra and fore and hind limbs. 
The shaft of the femur has an acute external margin, which culminates 
in a tuberosity or third trochanter. Two patellae are elongate ovals, convex 
in cross-section below. The inferior extremity of the fibula is especially 
stout in both diameters. The inner face is divided between a large vertical 
astragalar facet and a large posterior ligamentous fossa. The posterior face 
is marked by a prominent tuberosity, which bounds the peroneal groove 
exteriorly. The external face is convex and smooth. 
The calcaneum is similar to that of the last specimen, but one-half 
larger in all linear measurements. The astragalus is even more oblique on 
its inner face. The superior face is produced backward to a narrow point, 
bounding the inner face above, and is itself bounded externally by a groove 
directed forward and outward, which ceases at the superior plane. The 
neck is elongate and depressed. In the structure of this tarsus, we observe 
some of the most interesting characters of the Creodonta. On account of the 
inequality in the length of the astragalus and calcaneum, the proximal ends 
of the navicular and cuboid are not continuous as in the Carnivora. Hence, 
also, the cuboid possesses an oblique proximal inner facet for the astraga¬ 
lus, which is in line with the proximal face of the navicular without irreg¬ 
ularity. From this it follows that the head of the astragalus articulates 
with both navicular and cuboid by a continuous convex facet, and not, as 
in Mesonyx and Perissodactyla, by distinct facets. The cuboid is longer 
than wide, slightly convex proximally, concave distally, and concave on its 
exposed sides. There is no external tuberosity, but a moderate posterior 
one. The superior facet for the external face of the ectoeuneiform marks 
about the middle of the internal face of the cuboid. A bone resembling 
the navicular of the Carnivora is rather small and shallow, and has a moderate 
exterior anterior tuberosity. Tlie outline of the superior face is subrhomboid, 
the longest side being the external, wliere it is squarely truncate for contact 
with another bone. Where this side joins the posterior is a posterior 
tuberosity. Although this bone resembles the navicular of the Carnivora, 
I am not sure that it is that bone ; it differs considerably from that described 
