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fig. 5). The lateral portions of the distal trochlea are likewise divided by a sharper 

 ridge-like rising than in Osphranter rufus, Macropus major, or Phascolagus altus. The 

 longitudinal channel on the fore part of the shaft, answering to that marked n in fig. 4, 

 Plate CXVL, and bounded by the ridges q and o in fig. 4, Plate CXX., is both wider 

 and deeper in Protemnodon. The transverse diameter of the proximal half of the shaft 

 is relatively less than in Macropus affinis or in Phascolagus altus. 



§ 19. Macropus Titan (Metatarsal if). — The specimen of "fourth metatarsal," next 

 in size (Plate CXVIII. figs. 1-5), bears the same proportion to a femur assigned to 

 Macropus Titan as does the fourth metatarsal to the femur in Macropus major. The 

 proximal articular surface (ib. fig. 3) is smaller in proportion to the shaft in Macropus 

 Titan than in Phascolagus altus (Plate CXVII. fig. 5) ; the groove (g) is broader. The 

 shaft is relatively thicker, the ridge (r) is less produced, and the contour less convex 

 than in Plate CXVII. fig. 3. The anterior surface shows a wide and shallow longitu- 

 dinal channel along its proximal half, not present in Phascolagus ; the distal articulation 

 (Plate CXVIII. fig. 5) is relatively larger antero-posteriorly. 



§ 20. Palorchestes (Metatarsals ir & r). — The breadth of the middle of the shaft 

 of the fourth metatarsal of Macropus rufus is two thirds that of the same part of the 

 femur. The breadth of both fourth and fifth metatarsals, naturally united one third 

 down, is nearly equal to three fourths of the breadth of that part of the femur. 



The breadth of the middle of the shaft of the fourth metatarsal, the subject of 

 Plate CXVL fig. 1, is two thirds that of the same part of the femur, as shown at the 

 broken ends in figs. 1 & 2 of Plate CXV. The breadth of the naturally united fourth 

 and fifth metatarsals (Plate CXVL figs. 1 & 2), one third from their proximal ends, 

 equals four fifths of the same part of the femur of Palorchestes Azael. 



To this species, therefore, I provisionally refer the fossil subjects of figs. 1, 2, and 3 of 

 Plate CXVL The length of the fourth metatarsal in those figures is restored in 

 outline from an entire homologous bone of the same extinct species which had become 

 detached from the contiguous metatarsals, and which I have not thought necessary to 

 figure. 



In the fossil under description, to the great fourth metatarsal lacking the distal end 

 there remained attached the fifth metatarsal (ib. figs. 1 & 2, v), wanting only a portion 

 of the plantar or posterior wall of the proximal end; and, similarly attached, the 

 proximal half of the third metatarsal (ib. ib. m), exhibiting the characteristic macro- 

 podal slenderness. It is interesting to note, however, that the fifth metatarsal in the 

 huge extinct Kangaroo shows more nearly the normal proportions of the bone than in 

 the existing species, even the largest, as, e. g., Macropus rufus (Plate CXVL fig. 4, r) ; 

 and the more slender third metatarsal bone of Palorchestes (m, fig. 2, Plate CXVL) is 

 relatively less atrophied than in existing Kangaroos. Its proximal end (ib. fig. 3, m) 

 presents an oblong, subquadrate, almost flat surface for the ectocuneiform, and a trian- 

 gular surface on the inner side (ib. fig. 2, b) of the proximal end for part of the head of 

 the second metatarsal, which bone is wanting in the fossil. It articulates with the tibial 



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