186/.] DR. J. MURIE ON PHASCOLOMVS PLATYRHINUS. 813 



and thick, and presents a lesser curve, the interosseous interspace 

 being in consequence narrower ; tlie 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. platyrhi- 

 nus 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 out- 

 wards and backward^ and the ischium is unusually broad and flat 

 at its tuberositj', 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. loombat 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 pro- 

 cesses of the sacral and caudal vertebrae give a characteristic appear- 

 ance 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, j)oints down- 

 wards, 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 narrow- 

 est 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. la- 

 tifrons, and in breadth and thickness agree with those of P. ivombat. 

 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. womhof and that of P. platyrhinus are 



