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Show 1867.] DR. J. MURIE ON PHASCOLOMYS PLATYRHINUS. 813 and thick, and presents a lesser curve, the interosseous interspace being iu consequence narrower ; the two former, moreover, have a considerable forward bend in the shaft, which must admit of greater strength in the bones, and also give increased power to the muscles. Metacarpal Bones.-Of the bones of the fore paw P. platyrhinus agrees with P. wombat in that the metacarpals are somewhat longer as compared with the digits than is the case in P. latifrons. Bones of the Hind Limb. The Pelvis.-The sacral portion of this has already been referred to in connexion with the region of the spine. In P. platyrhinus the entire pelvic bones correspond with the powerful build of the body, being uncommonly strong and of great breadth and length. In the general form of the ilium, ischium, and pubis P. platyrhinus more nearly resembles P. wombat than these two species do P. latifrons. Between P. platyrhinus and P. wombat, besides difference in size, the former has more marked muscular ridges and depressions. The anterior spinous process of the ilium in the first sweeps well outwards and backwards, and the ischium is unusually broad and flat at its tuberosit}-, the inner prominent border bending more towards the transverse processes of the caudal vertebrae. The axis of the pelvic bones, taken in a line from the spine of the ilium to the ischium, is somewhat straighter in P. wombat than in P. platyrhinus. Possibly this may be due to sex more than to specific divergence. In P. latifrons the very narrowed condition of the transverse processes of the sacral and caudal vertebrae give a characteristic appearance to the pelvic region as seen dorsally. The tuberosities of the ischia not only seem wider apart, but, in comparison with the size of the bones, are substantially wider than in P. platyrhinus or P. wombat. The ventral surface, corresponding with the false pelvis of human anatomy, of each ilium in P. latifrons is more deeply grooved; and the anterior border of the bone, more unusually prominent, points downwards, and not outwards as in the Platyrhine and common species. The anterior spinous process has a somewhat inward and forward curve-in this manner less backwardly falciform than in the two other species. The symphysis and the arch of the pubis are narrowest in P. latifrons -, but the rami and tuberosities of the ischia diverge outwards and upwards (backwards). Thus each ischium has a very narrow and laterally compressed tuberosity compared with that of P. wombat and P. platyrhinus, in the latter of which the enormously expanded and roughened ischial tuberosities forcibly indicate great muscular attachment and increased volume and strength in the hinder parts. Marsupial Bones.-These are proportionally the longest in P. latifrons, and in breadth and thickness agree with those of P. wombat. P. platyrhinus has them relatively the broadest. In this last also there is usually a larger interspace or foramen where they arch between the symphysis and the ilio-pubic ridge. Femur.-The femur of P. wombat and that of P. platyrhinus are |