496 



PdhrchestfX Aztnl. 0.ij,li,-a„hr rufus. 





in. 



lines. 



in. 



lines. 



Length from head to subsidence of procnemial ridge . 



7 



6 



5 



3 



Fore-and-aft diameter at upper part of procnemial ridge 



3 



5 



2 







Transverse diameter of shaft halfway down procnemial 













1 



to 



/ 



1 







Span of excavation between procnemial ridge and fibular 













2 



4 



1 



6 





3 



10 



2 



8 



§ 14. Palorchestes (Calcaneum). — In Macropus (Osphranter) rufus the length of the 

 calcaneum exceeds the transverse breadth of the distal end of the femur by two sevenths ; 

 the extreme breadth of the calcaneum is one third greater than that of the middle of 

 the shaft of the femur. By these proportions I am guided in the choice of the two 

 fossil calcanea (figs. 4 & 5, Plate CXV.), and refer the longer bone to Palorchestes. 



The length of the subject of fig. 5, Plate CXV., exceeds the transverse breadth of 

 the distal end of the femur (ib. fig. 2) by two sevenths. The length of the calcaneum 

 (ib. fig. 4) exceeds the transverse breadth of the distal end of the femur (ib. fig. 3) by 

 one fourth. The breadth of the calcaneal process of fig. 4 is equal to that of the longer 

 calcaneum, fig. 5. 



On the grounds subsequently to be adduced for concluding the leg and foot of 

 Procoptodon to have been shorter in proportion to its length than in Macropus, I 

 therefore assign the shorter and thicker calcaneum to that genus, together with the 

 portion of femur (fig. 3), which shows more generalized characters, or those less strictly 

 macropodal, than the femora assigned to Palorchestes, Macropus, and Sthenurus. 



The figures of both the calcaneal fossils may be compared with those of the existing 

 Macropus rufus (Plate LXXV. fig. 6), and with the characters described, p. 390. 



§ 15. Macropodidce (Metatarsals). — The hind foot in Kangaroos exhibits an extreme 

 modification of the osseous structure (ante, pp. 390-393, Plate LXXV.). The inner 

 toe (/of the typical pentadactyle foot) is suppressed; the metatarsals of the toes 

 // & in are long and filamentary, supporting a pair of small pendent fur-cleansing 

 claw-toes ; that of the toe iv is both long and large, with characteristic modifications 

 of its proximal end ; that of v is much less in size, Avith the shaft compressed, but 

 supporting, like the metatarsal of ir, a toe with a quasi hoof for station and progression. 



In Plate CXVI. fig. 4, is given a view of the fourth (ir) and fifth (r) metatarsals, 

 natural size, of the right hind foot of Macropus rufus; two other views of the same 

 bones are given in Plate LXXV. I may here add to the previous description, as a 

 guide for distinguishing the right from the left fourth metatarsal, the following 

 characters : — Below the proximal articular surface the inner (tibial) side of the shaft 

 shows a bilobed articular surface (Plate CXX. fig. 3, m, n), the subtriangular expanded 

 portions being united by a narrow tract, varying in breadth, and linear in some 

 species; beneath this articular surface there is a large rough triangular depression 



