third digits are quite distinct; but the distal end is entire only in the first, or that of the hallux, which measures 1⋅85 inch in length. It has a pulley-shaped articular surface, and is 0⋅5 inch wide. The shaft of the bone is greatly compressed from side to side, as in Scelidosaurus. The second and third metatarsals are much broader and stouter, with flattened superior faces. They also seem to have been longer than the first. The fourth metatarsal looks, at first, as if it were much wider than the other; but, on close examination, I think I can trace a line of matrix separating a true fourth metatarsal, of about the same size as the others, from a slender fifth metatarsal. A basal phalanx, which seems to have belonged to the middle digit, is 1 inch long, 0⋅6 inch wide at the proximal, and 0⋅35 inch at the distal end. The pes of Hypsilophodon, thus, was either tetradactyle or pentadactyle.
The length of the trunk and tail of Hypsilophodon was probably about 412 feet; and, in all likelihood, it was mainly herbivorous.
[For description of Plates I. & II. see p. 50.]
On my way to Birmingham, in October 1867, I chanced to meet with Prof. Phillips; and mentioning some palæontological inquiries, chiefly relating to the Ichthyosauria (with which I then happened to be occupied), he very kindly urged me, as I returned to London, to pay a visit to the collection under his charge in the University Museum at Oxford. I did so; but as we were traversing the museum towards the Ichthyosaurian cases, we stopped at that containing the Megalosaurian remains, and I may say with Francesca—
"Quel giorno più non vi leggemmo avanti."
It is indeed a wonderful collection, ample enough to occupy the working hours of many a day; and it was particularly attractive to me, as some difficulties in the organization of Megalosaurus and its allies had long perplexed me.
As Prof. Phillips directed my attention to one after the other of the precious relics, my eye was suddenly caught by what I had never before seen, namely the complete pectoral arch of the great reptile, consisting of a scapula and a coracoid ankylosed together. Here was a tangle at once unravelled. The coracoid was totally different from the bone described by Cuvier, and by all subsequent anatomists, under that name. What then was the latter bone? Clearly, if it did not belong to the shoulder-girdle it must form a part of the pelvis; and, in the pelvis, the ilium at once suggested itself as the only possible homologue. Comparison with skeletons of reptiles and of birds, close at hand, showed it to be not only an ilium, but an ilium which, though peculiar in its form and proportions, was eminently ornithic in its chief peculiarities.
