OCR Text |
Show 1894.] IN THE BRITISH MUSEUM. 109 Length Width of proximal end .... Width of distal end Width of shaft at narrowest point Circumference of shaft, at narrowest point Width of middle trochlea . M., sp. cm. 31-6 11-5 1.1-9 5-4 136 4-7 M. maximus. cm. 37-0 (?) 14-5 8-0 (?) 20-0 5-2 M. hildebrandti, cm. 27'5 95 100 4-5 11-0 43 At the proximal end the inner glenoidal cavity is the deeper of the two; it is oval in outline, the long axis being antero-posterior, and its front and hind borders are produced upwards into blunt points, of which the hinder is much the higher. The outer glenoidal cavity is shallow, and slopes down at its antero-external edge, where it has no well-defined border. These two cavities are separated by a surface, plane behind and slightly concave from side to side in front; there is no distinct median groove such as is said to occur in JZ. hildebrandti. There is no trace of an intercondylar process. As in the other members of the genus hitherto described, the anterior surface of the shaft is deeply depressed in the middle line at the upper end, the depression dying away downwards, till a little above the trochleas the bone is slightly convex from side to side. At the deepest part of the depression, about 5 cm. from the proximal end of the bone, the foramina interossea open. They are about 1 cm. apart and at the same level, thus differing from JS. hildebrandti, where the outer is rather above the inner. Immediately below them there is a large rugose tuberosity for the insertion of the tibialis anticus. In the upper part of the outer surface is a rather broad groove passing obliquely from the anterior face to the posterior, where it dies away. The talon consists mainly of a broad blunt ridge, continuous with the upper end of the middle metatarsal and lying slightly to the outer side of the middle line. Internal to this is a broad, short, and very shallow groove, bounded internally by a low blunt tubercle lying immediately above the inner interosseous foramen. The lower part of the posterior surface closely resembles in general appearance that of AS. hildebrandti, but is remarkable from the fact that it shows a distinct trace of the presence of a hind toe. Although several authors state that AHpyornis possessed four toes, I a m not aware that any trace of the presence of a hallux is to be found in any specimen described till now. On the postero-internal surface, about 9 cm. above the distal end of the inner trochlea, is a bony projection, measuring 3 cm. from above down, and 1 cm. from side to side; it rises to a height of about |