202 
scribed as postero-internal till it comes to occupy nearly its whole 
width. A rough oval tuberosity (Figs. 8, 9, C) is developed 
upon the posterior border of the shaft a little below the level of 
the commencement of the articular surface, and below this there 
is a gradual reduction in the size of the shaft which, moreover, 
loses its trilateral character. Below the articular surface the 
shaft assumes the form of a cone, which in most of the specimens 
tapers rather abruptly to a blunt point. In the longest speci- 
men the taper is more gradual, and the length below the articu- 
lar surface, in this, is consequently greater. 
The length of a large fibula, apparently complete as to its 
length, and of about the same size as an imperfect specimen 
belonging to one of the large tibio-tarsi, is 9£ inches, while that of 
the smallest is 84 inches. The antero-posterior diameters of the 
heads of these two bones, measured obliquely in the direction of 
the longer axis, are 2," inches and 2 inches respectively. Seven 
fibule, only, were collected, but these are all in good preservation 
with the exception of the lower pointed extremity, which is 
broken off in most of them. 
Tarso-metatarsus.—The ecto-condylar surface (Pl. v., fig. 3, 
£ C) is subquadrangular and flat, with a slight slope downwards 
as it extends outwards. That of the ento-condyle (fig. 3, Z @) 
somewhat exceeds a semicircle in shape; its transverse diameter 
is about equal to, and the antero-posterior diameter greater than, 
those measurements in the ecto-condyle. In the latter diameter 
it is slightly concave, and in the former greatly so, this character 
being principally due to the elevation of the inner margin into 
an elevated lip or crest (A), which rises a little higher than the 
anterior entocondylar process. This crest frequently exhibits a 
slight, externally directed curvature (fig. 1, 4). The inter- 
condylar tract, marked at about its centre by a shallow depres- 
sion, rises in front into an obtusely angulated intercondylar ' 
process (fig. 1, B). 
On the posterior aspect of the upper extremity there is a single 
thick, prominent and undivided hypotarsus (Pl. v., fig. 2, C) 
which rises above the articular surface as a sub-conical promi- 
nence, and reaches a somewhat greater elevation than the 
anterior intercondylar process. The inner surface of the hypo- 
tarsus is marked by a shallow groove which begins a little below 
its summit and curves somewhat forwards as it descends. This » 
groove disappears under a broad but thin bridge of bone (fig. 2, 
D) which covers the opening of the posterior ent-interosseous 
canal, and below this it continues more or less distinctly for some 
distance down the postero-internal surface of the shaft. 
The hypotarsus extends, mesially, down the shaft as a broa 
angular ridge with gradually diminishing elevation, which, how. 
