The Quarterly journal of the Geological Society of London (13204955875)

ANNIVERSARY ADDRESS OF THE PRESIDENT. 55
the last touch of the femur or propodial element of the limb, and,
thrust out of the epipodium, it appears henceforth to belong to the
Fig. 9. — Hind limb of Sauranodon, Marsh.
T, the tibia ; i, the intermedium ; F, the fibula ; t, os tibiale ; ./, fibulare
c, c, ossa centralia.
mesopodium, as 0. C. Marsh has remarked in Sauranodon. From
this arrangement to such a mesopodium (carpus, tarsus) as that of
the living Cryptobranchus japonicus (fig. 13), or of the common land-
Salamander (figs. 11, 12), is but a small step.
Another morphological question upon which the Enaliosaurian
paddles throw light is the primitive duality or singleness of the os
centrale of the carpus or tarsus (mesopodium), about which opinions
differ; for in some extant Amphibia the carpus (tarsus) contains one
os centrale, while in others two ossa centralia are present ; and this
difference has been occasionally observed in the right and left carpus
of the same individual. Now in Sauranodon (fig. 9), Ichthyosaurus
(fig. 10), Pliosaurus portlandicus, Owen (fig. 8), and, I believe, also
in Plesiosaurus Manseli, the proximal row in the mesopodium (carpus
or tarsus) comprises four ossicles, of which, since the two lateral
ossicles must by their relations be the os tibiale, os fibulare (os

radiale, os ulnare), the two middle cannot be other than two ossa