1900.] FOSSIL MAEStTPIAl FROM TASMANIA. 789 



in certain respects have much the same relationship one to another 

 that they have in the Macropodidae, They differ markedly from 

 those of the Dasyuridse, and still more from those of the Phalan- 

 geridse. The bone gradually spreads out towards the crest, which 

 curves out as in the Phalangeridae, but in the fossil the crest is 

 formed by the union of the gluteal and sacral surfaces. The bone 

 is roughly triangular in section, with two broad and one narrow 

 side, much as in the Macropodidae, from which, however, it differs 

 strongly in the gradual swelling out towards the crest. The 

 acetabular border, which is rouuded proximally, becomes more and 

 more angular distally and curves outwards to the external limit of 

 the crest. The pubic border, which is distinctly marked along its 

 whole length, much as in Macropodidae, is very sharply denned 

 distally, and between these two borders" runs the iliac surface 

 which is distinctly concave distally. The ilium in its broad, 

 flattened distal part with outcurving crest bears only a superficial 

 resemblance to that of the Phalangeridae, for whereas in the latter 

 the acetabular border lies almost in the middle line of the expanded 

 surface, in the fossil it forms the lower and outer boundary of 

 this, the iliac surface being as it were pushed forwards and down- 

 wards so as to form, as in the Macropodidae, a very distinct antero- 

 inferior surface. From that of Dasyurns and Perameles the bone 

 differs in that the iliac border does not meet the acetabular, and so 

 obliterate the iliac surface in the upper and distal part, though this 

 obliteration is not quite complete in all specimens of Dasyurus. 



The marsupial bones are well developed, and fortunately one of 

 them is in a good state of preservation. It is straight, flattened, 

 and considerably expanded at the proximal extremity, where, as 

 in the Wombat, there are two distinct surfaces for articulation 

 with the pubis. They differ markedly from those of the Phalan- 

 geridae both in size and in the absence of the curve which is 

 characteristic of the bone in such forms as Triehosurus. The 

 length of the bone is 55 mm. ; that of the corresponding bone in 

 a Triehosurus, the femur and skull of which are of approximately 

 the same length as those of the fossil, being only 31 mm. In 

 shape the bone is closely similar to that of the Wombat, though 

 relatively larger ; in fact it is as large in proportion to the ilium 

 as in Phascolarctos, though it is markedly different from that of the 

 latter in being straight instead of strongly curved. The width of 

 the expanded proximal end is 22 mm. ; at 11 mm. from this end 

 the width is 9 mm. ; at 15 it is 6 mm., and this width is continued 

 to the distal end. 



Sacrum. 



Only a broken portion of the sacrum is preserved, showing the 

 bodies of three fused vertebras. The transverse processes are 

 too broken to allow of the method of attachment of the ilia being 

 determined, but the bodies and processes of the three are firmly 

 fused together. The neural spine of the first is broad and flattened, 

 measuring 14 mm. in length ; the total height cannot be ascertained, 



52* 



