493 



present fossil in the upper portion of the bone, as the partial division of the outer 

 condyle (fig. 2, v) by the channel (w), and the deep rough oblong fossa (y) above that 

 condyle, do in the lower portion. 



Guided by the proportions of the femur in Macropus major and Macropus rufus, 1 

 estimate the subject of fig. 1, Plate CXV., to include the proximal third of that bone 

 in Palorchestes Azael, or in a species akin to a Macropus of that size ; and I suspect, as 

 the upper portion of the great trochanter is still epiphysial, or but partially united to 

 the shaft, that this thigh-bone may have come from a not fully mature individual. 



Since in Macropus rufus the extreme breadth of the proximal end of the femur 

 exceeds that of the distal end by 3 lines, I estimate the difference in those admeasure- 

 ments of the ends of the fossil femur, figs. 1 & 2, in Plate CXV. to be within the limits 

 of individual character in Palorchestes ; the breadth of the shaft, where broken across, 

 in both upper and lower portions is the same and the circumference in both is 5 inches. 

 The somewhat larger proportional proximal end, due to the development of the great 

 trochanter, may be taken as one of the differential characters of the present huge 

 femur as compared with that bone in the largest living Kangaroos. 



The great trochanter is continued as a strong ridge (ib. fig. 1, g) 5-| inches along the 

 outer border of the bone ; but the trochanter itself (/') is, relatively, less raised above 

 the head {a) than in Macropus major. The articular surface of the head is less convex 

 than in Macropus rufus, and the anterior concavity between it and the trochanter is 

 less marked. The demarcation of the summit of the trochanter by the antero-internal 

 channel is more feebly given in Palorchestes. The upper surface of the neck of the 

 femur (c) is relatively broader in Palorchestes than in Macropus. 



The lesser trochanterian ridge (n) is more posterior in position than in Macropus 

 rufus, in which its free margin just comes into view when the femur is seen from the 

 front ; this is not the case in Palorchestes, in which the ridge descends to the parallel 

 of the beginning of the posterior ridge, which resembles at its most prominent part (p) 

 a third trochanter. The trochanterian fossa (fig. 1, /) has the extreme generic or 

 family depth in Palorchestes ; it forms a long narrow cavity, undermining the hinder 

 basal part of the great trochanter. 



From the summit of this trochanter (/) to the third trochanter {p) being 6| inches, 

 the total length of the femur of Palorchestes may be reckoned, from the analogy of 

 Macropus rufus, to have been not less than 18 inches; in that recent species it is 

 10^ inches. The epiphysial line of the great trochanter is distinct, but confluence of 

 the central part has kept the process in place in the present fossil. 



The upper end of the linea aspera is preserved, expanding to form the process^). 



At the distal end of the femur (ib. fig. 2) the chief distinction of Palorchestes from 

 Macropus is in the relatively narrower postintercondylar fissure (w) and its minor ex- 

 pansion, where it is closed anteriorly. The depression (y) is strongly marked in 

 Palorchestes. The epiphysial line is traceable in the fossil ; a wedge-shaped process at 



52* 



