326 



THE HIND FOOT OR PES. 





The insect- and root-eating, ground-dwelling Bandicoots 

 (Peramelidcz) differing in many other respects from the 

 Kangaroos, have their hind-foot constructed on exactly 

 the'same type as in Macropus, even to the relative length 

 of the different digits, though there is often a. rudiment of 

 the metatarsal of the hallux. In one 

 remarkable genus (Choeropus), already 

 mentioned on account of the peculiar 

 structure of the manus (see Fig. 104, 

 p. 281), the same type is carried to a 

 great extreme, the fourth toe (see Fig. 

 124) remaining of a prodigious size 

 and the fifth being reduced to even 

 smaller dimensions than the second or 

 third. 



Monotremata. — In both species 

 the seven usual bones of the tarsus are 

 complete and distinct, 1 and the five 

 digits have the normal number of pha- 

 langes. 



In the Ornithorhynchus the proximal 

 articular surface of the astragalus is 

 divided by a deep groove into two 

 distinct heads, one for the tibia, and 

 the other for the fibula, the latter 

 being the larger of the two ; the inner side has a cup- 

 shaped socket, into which fits an incurved conical process 

 from the lower end of the tibia. The tuberosity of the cal- 

 caneum is broad and bifid at the extremity, and directed 



1 It has been stated that the cuboid in the Ornithorhynchus is divided 

 into two bones, as in some reptiles, one supporting the fourth and the 

 other the fifth metatarsal; but this is not the case in any specimen 

 which I have examined. 



Km 



.24. 



Bones of right 

 foot of Choerofins casta- 

 notis (nat. size). 



