PROFESSOR OWEN ON THE FOSSIL MAMMALS OF AUSTRALIA. 



561 



apex is 6 inches : this production is more conspicuous at the fore (Plate XLVIII. fig. 1 , h) 

 than at the back part (Plate XLIX. fig. 1). The margin of the articular surface is 

 sliglitly prominent, through the sudden contraction of the rough surface of the neck ; 

 but this is chiefly at the fore part (Plate XLVIII. fig. 1, d), towards which aspect the 

 head slightly inclines. At the back part of the neck, just beyond the head, there is a 

 low ridge 1^ inch long (Plate XLIX. fig. 1, e) parallel to the margin of the articular 

 surface. 



Tlie rugged surface of the great trochanter commences at the middle of the upper 

 part of the neck, with a moderate elevation and a border convex towards the head (Plate 

 XLVIII. fig. 2, f) ; its fore-and-aft breadth here is 3^ inches, but the process expands 

 as it recedes from the head, sloping downward to a breadth of 4 inches 10 lines ; its 

 outer expanded termination is subbilobed, the posterior lobe (ib. h) being most pro- 

 duced outward ; the anterior one (ib. g) is continued furthest down the shaft. 



Anteriorly the great trochanter is defined by the abrupt rising of the rugged surface 

 from the smooth surface of the neck along a curved line (ib. fig. 1, ?'), which bends 

 round the lower part of the anterior lobe (ib. fig. 1, g),: this is continued upon the 

 fore part of the shaft near its outer margin for an extent of 5 inches from the upper 

 surface of the lobe; the posterior lobe (Plate XLIX. fig. 1, 1i) extends a shorter 

 way down the outer surface of the femur, and is defined, or rises, very abruptly from the 

 smooth tract of that part of the shaft. The posterior part of the trochanter projects as 

 a thick oblong tuberosity (ib. fig. 1, Jc) above the trochanterian depression (ib. I) : the 

 mouth of this depression is 3 inches 8 lines in length, 1 inch in breadth, opening parallel 

 with the lower margin of the neck, and is 3 inches in depth. Beyond the depression 

 the posterior margin of the trochanter is less defined from the femoral shaft than is the 

 anterior one. The neck of the femur (Plates XLVIII. & XLIX. m) begins by hardly a 

 less diameter than the head from above downward, and augments in that direction as it 

 extends outward ; it is rapidly compressed from before backward, as it recedes, especially 

 where it is continued into the trochanterian fossa (l) ; its upper margin is slightly concave 

 from within outward, convex from before backward, 2 inches broad in that direction ; 

 the lower margin is 2 inches 6 lines. This margin is not uniformly convex across, 

 but is remarkable for the production of its hinder half into a long narrow elliptical rough 

 ridge, representing the small trochanter, which is 6 inches in length and 1^ inch across 

 the middle (Plate XLVIII. fig. 1, 



The lower ends of this and of the anterior tuberosity of the great trochanter are on 

 the same transverse parallel, at which the proper shaft of the femur may be said to 

 commence. This is defined by a gentle concave curve in both outer and inner sides, the 

 least transverse diameter being 4 inches 5 lines. At the upper half of the shaft the 

 fore-and-aft thickness decreases from the outer to the inner border, which is reduced to 

 2 inches before rounding ofi". This border gains in thickness as it approaches the lower 

 end. 



The outer side of the compressed shaft preserves a thickness of about 2^ inches along 



4g2 



