494 



both the outer (z) and the inner (z') borders rises as if to clamp more securely the 

 epiphysis to the shaft. 



The following admeasurements exemplify the difference of size between Palorchestes 

 Azael and Macropus rufus, the measured femur of the latter being of a full-grown 

 male : — 



Palorchestes Azael. Macroj)us rufus. 

 in. lines. in. lines. 



Extreme breadth of proximal end of femur ... 4 9 2 9 



Extreme breadth of middle of shaft of femur ..18 10 

 Extreme breadth of distal end of femur .... 3 9 2 5 



§ 10. Sthenurus Breliusl (Femur). — To this species I incline to refer a distal end of 

 the left femur, which shows, besides the well-marked cavity (y) on the anterior and 

 posterior part of the distal end of the diapophysis, a similar but shallower large depres- 

 sion on the inner posterior side. Into the lower border of both these depressions the 

 wedge-like processes of the epiphysis project. The relative breadth of the intercon- 

 dylar fossa agrees with that in Palorchestes, and shows as little expanse of the anterior 

 closed end. The fore-and-aft extent of the outer condyle is 3 inches 3 lines ; and the 

 breadth of both condyles, if the inner one was entire, would be at least as much. The 

 weight and petrified state of this fossil are remarkable. 



§11. Procoptodon I (Femur). — Of the series of femoral fossils with the depression (y) 

 less marked, and seemingly blocked or filled up by the epiphysial " clamping " process 

 (z), a specimen is selected to exemplify this character in figure 3 of Plate CXV. 



The postintercondylar fissure (u) is more expanded anteriorly, and there takes a 

 winding course about a flat part or process (t') of the inner condyle, which process 

 extends outward into the expanded part of the intercondylar cavity. The small pit on 

 the outer side of the posteriorly projecting part of the outer condyle is here represented 

 by a notch. 



I refer, provisionally, this type of femur to the genus Procoptodon ; the present 

 fragment might belong to a Procopt. Rapha. True, the fore-and-aft diameter of the 

 outer condyle is but 2 inches 3^ lines, not exceeding that in the recent Osphranter 

 rufus (Plate LXXVII. fig. 3) ; but the breadth of the distal end of the femur in 

 Procoptodon Rapha is 3 inches 1 line, whilst in Osphranter rufus it is but 2 inches 

 3 lines, the two diameters being subequal in the recent Kangaroo compared. The 

 excess of transverse diameter in Procoptodon Rapha depends on the greater develop- 

 ment of the inner condyle, which equals that of the outer one. The small depression 

 for the lateral ligament on the inner non-articular surface of the inner condyle is deeper 

 and better defined than in Macropus or Osphranter. 



A second example of the distal end of a femur (left) with the " procoptodont " 

 character of the depression (y) exceeds in size that of Procoptodon Rapha as much as 

 the mandible and teeth of that species surpass those parts in Procoptodon Rapha. I 

 refer, therefore, the present fossil to Procoptodon Goliah. The line of epiphysial 



