"278 The American Geologist. May, 1396 
The tibia and fibula have not been separated from the 
matrix, but apparently exhibit the same proportions as shown 
in the fore Limb; the distal extremity of the former is pro- 
portionately of less diameter and the articular surface for the 
astragalus is considerably less than in the living C.familiaris; 
the bone is prolonged at its internal side, forming the internal 
malleolus, which is however not so well developed and does 
not project so much beyond the astragalus. The fibula artic- 
ulates to a greater extent upon the anterior lateral surface of 
the astragalus, this being due to the very strong outward 
position of the external surface of the astragalus, as it 
approaches the posterior. 
The tarsal bones (fig. 9), with the exception of the cal- 
caneum and astragalus, are very regularly formed with squar- 
ed edges and flattened surfaces; in this latter bone the 
articular surface for the tibia is rather narrow, and, viewed 
in an upright position, articulation with the tibia is nearer 
the proximal end of the astragalus. The bone when viewed 
directly from the front will show the two sides, and particularly 
the external more exposed, the articulating surface for the 
fibula being more anterior than in the living species. The 
calcaneum is of the usual shape, perhaps proportionately 
somewhat more strongly developed in length, the width how- 
ever being of normal size. The navicular is elongate and 
narrow, the greater axis being horizontal ; it articulates almost 
entirely upon the two cuneiforms. There is not the usual up- 
ward internal extension covering the internal edge of the 
astragalus as in the living species. 
The cuboid is also elongate and narrow, its greater axis 
being, however, vertical ; it has the same measurements as the 
navicular, but in reverse position. It does not articulate upon 
the external edge of the internal cuneiform and only very 
■slightly upon the fifth metatarsal, the articulation being 
lateral. In C.familiaris, we find this bone articulating upon 
quite two-thirds of the surface of the fifth metatarsal. The 
cuneiform . bones when viewed from the front show regular 
flat edges and form nearly perfect squares: the difference 
in size between the internal and middle bones is not so great 
as in the living species. In the specimen under consideration 
only the first phalanges of digits I-IV are preserved and the 
