495 



suture is better marked than in the femoral specimen of the smaller species, and the 

 present fossil has belonged to a less aged individual. 



The characters of the intercondylar groove are repeated, except that the process from 

 the inner condyle encroaching on the expanded end of the groove is less defined. 



The breadth of the distal end of this femur, if the inner condyle were entire, would 

 be 3 inches 6 lines ; the antero-posterior extent of the outer condyle is 2 inches 9 lines. 



§12. ProtemnodonX (Femur). — In the fossil here referred to that genus the small 

 trochanter projects so as to come well into view, looking upon the front of the shaft. 

 Between the lower ends of the two trochanters at the middle of the back part of the 

 shaft begins a sharp, well-defined ridge, which extends down to the outside of the 

 " third trochanter." This character is not presented in the fossil femora referred to 

 Macropus, Sthenurus, Procoptodon, or Palorchestes. The head is less convex above 

 than in Palorchestes. The distinct epiphysial cap of bone which overlies what seems 

 to be the diapophysial part or basis of the articular head is well marked in this fossil. 

 The length from the top of the head to the commencing expansion of the distal end of 

 the shaft is 10 inches ; the circumference of the middle of the shaft is 5 inches. 



§ 13. Palorchestes X (Tibia). — The locality of the discovery of the fine portion of tibia 

 figured in Plate CXXXL, with its characters and proportions, leads me to refer it to 

 the same genus and species as the mandibular fossil figured in Plate CVI. 



If the subject of Plate CXXXL be compared with the corresponding views of the 

 entire tibia of the large male Eed Kangaroo (Plate LXXIV.), the association of the 

 peculiar characteristics of the macropodal tibia with the grand proportions of that bone 

 in Palorchestes will be readily appreciated. 



The length of the present fossil remnant from the proximal end of the bone to the 

 subsidence on the shaft of the procnemial plate is 7-g inches. The fore-and-aft diameter 

 of the tibia, at the upper part of the plate, is 3 inches 5 lines ; the span of the exca- 

 vation between the procnemial and ectocnemial plates or ridges is 2 inches 4 lines ; 

 the antero-posterior diameter of the head of the tibia is 3 inches 10 lines; the breadth 

 of the back part of the tibia, at 5 inches below the articular head, is 1 inch 6 lines. 

 The head of the tibia is in a state of epiphysis ; its undulatory course along the inner 

 side of the bone is shown in fig. 4, but partial confluence, as in the case of the epi- 

 physis of the femur of probably the same individual Palorchestes, has tended to retain 

 the epiphysis in place, notwithstanding the movements and shocks of alluvial transport 

 through which, seemingly, the fractures of the fossil are due. 



The inner articular facet (ib. fig. 5), the only one preserved on the head, is relatively 

 more extensive and more concave transversely than in Macropus rufus. The hind 

 surface of the shaft (ib. fig. 3), continued down from that articular surface, is thicker 

 and more convex across ; it contracts in the large recent Kangaroo to an angular ridge, 

 sharply dividing the hinder from the antero-internal surface of the shaft of the bone. 



The following are a few comparative dimensions of the fossil tibia : — 



