LOWER LIAS. 
17 
favouring flexion and extension, or motion of the foot io and fro. Its distal 
surface is convex in the same direction, and is sinuous transversely. 
The calcaneum (ib., figs. 1 and 3, i) articulates with the distal end of the 
fibula (fig. 1, 67) and with the outer third of tlie same surface of the tibia (fig. 3, i). 
The next most intelligible tarsal bone is that (figs. 1 and 3, b) which articulates 
with the calcaneum (/) and with the two outer metatarsals {{v and v). Its largest 
surface is turned forward or upward (fig. 1, b). Its posterior surface (fig. 1, b) 
is a smaller convex protuberance ; this bone answers to the “ cubo'ides.’^ 
At the back part of the tarsus there projects the base of a wedge-shaped bone, 
(fig. 3, <’) seemingly partially dislocated backward, which mainly supports the 
middle metatarsal (m), and extends partly over the fourth (fig. 3, iv). The apex 
of this bone appears on the front side of the tarsus (fig. 1, e) in the interspace 
between the astragalus («), cuboides {b), the third and fourth metatarsals. I regard 
tins bone, therefore, as answering to the ecto-cuneiform ; I cannot discern any 
trace of other cuneiform bones, the fibro-cartilage by which the interspace between 
the bone («), and the first and second metatarsals, was most probably occupied, 
held partly the place of the meso- and ento-cuneiforin bones. From this it appears 
that the tarsus of SceUdosaurus includes but four bones, as in the Crocodile, 
Tab. XI, fig. 4. In the Lizard {Varcums), fig. 3, an ossification in the fibro-car- 
tilage at the base of the second metatarsal establishes the “ meso-cuneiforme,^’ and 
leaves the “ ento-cuneiforrae ” to combine with the naviculare and astragalus in the 
bone («). 
The metatarsus of SceUdosaurus consists of five bones. Of these, the fifth 
(Tab. IX, figs. 1 and 3, d) is abortive, and adherent to a rough ridge on the outer 
part of the base of the fourth metatarsal, with its proximal half extending over the 
interspace between that bone and the cuboid to articulate with the latter. It was 
not, however, flattened and expanded, as in the Crocodile (Tab. XI, fig. 4, v), but 
was slender and styliform, if we may judge by the proximal end which fortunately 
remains attached in the left hind foot of SceUdosaurus (Tab. X, fig. 1,^,). It 
most probably did not support a toe, or make any distinct appearance in the entire 
foot. The other four metatarsals support each a fully-developed toe, with the 
progressive increase in the number of phalanges characteristic of saurian Reptilia ; 
the first having 2, the second 3, the third 4, and the fourth 5 phalanges. 
The metatarsal of the first or innermost toe (Tabs. X and XI, i), is 2 inches 9 
lines long. With its proximal end laterally compressed, and abutting against the 
corresponding end of the second metatarsal, which is much expanded in that 
direction. The distal end of the first is 13 lines in breadth, with a convex articu- 
lar surface. The first phalanx of the toe (d is 2 inches long, 14 lines across the 
base, convex transversely towards the dorsum of the foot, flattened transversely and 
slightly concave lengthwise, towards the sole. The ungual phalanx is 1^ inch in 
3 
