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The tibia has a great anterior or procnemial ” crest, convex 
on the inner, and concave on the outer, side. Nothing com- 
parable to this exists in other reptiles, but a correspondingly- 
developed crest exists in the great majority of birds, especially 
such as have great walking or swimming powers. 7. The lower 
extremity of the fibula is much smaller than the other; it is, 
proportionally, a more slender bone than in other reptiles. In 
birds the distal end of the fibula thins away to a point, and it 
is a still more slender bone. 8. Scelidosaurus has four com- 
plete toes, but there is a rudiment of a fifth metatarsal. The 
third or middle toe is the largest, and the metatarsal of the 
hallux is much smaller at its proximal than at its distal end. 
Iguanodon has three large toes, of which the middle is the 
longest. The slender proximal end of a first metatarsal has 
been found adherent to the inner face of the second, so that if 
the hallux was completely developed it was probably very small. 
No rudiment of the outer toe has been observed (Plate XXYHI. 
fig. 7 ). It is clear, from the manner in which the three principal 
metatarsals articulate together, that they were very intimately and 
firmly united, and that a sufficient base for the support of the 
body was afforded by the spreading out of the phalangeal regions 
of the toes. 
From the great difference in size between the fore and hind 
limbs, Mantell, and more recently Leidy, have concluded 
that the Dinosauria (at least, Iguanodon and Hadrosau- 
rus) may have supported themselves, for a longer or shorter 
period, upon their hind legs. But the discovery made in the 
Weald, by Mr. Beckles, of pairs of large three-toed footprints, 
of such a size and at such a distance apart that it is difficult to 
believe they can have been made by anything but an Iguanodon, 
lead to the supposition that this vast reptile, and perhaps others 
of its family, must have walked, temporarily or permanently, 
upon its hind legs. However this may be, there can be no 
doubt that the hind quarters of the Dinosauria wonderfully 
approached those of birds in their general structure, and there- 
fore that these extinct Eeptiles were more closely allied to 
birds than any which now live. 
But a single specimen, obtained from those Solenhofen slates, 
to the accident of whose existence and usefulness in the arts 
palaeontology is so much indebted, affords a still nearer approxi- 
mation to the “ missing link ” between reptiles and birds. This 
is the singular reptile which has been described and named 
Compsognathus longipes by the late- Andreas Wagner, and 
some of the more recondite ornithic affinities of which have 
been since pointed out by Gregenbaur (Plate XXVIII. fig. 2). 
Notwithstanding its small size (it was not much more than two 
feet in length), this reptile must, I think, be placed among, or 
